docs: add qemu-block-drivers(7) man page

Block driver documentation is available in qemu-doc.html.  It would be
convenient to have documentation for formats, protocols, and filter
drivers in a man page.

Extract the relevant part of qemu-doc.html into a new file called
docs/qemu-block-drivers.texi.  This file can also be built as a
stand-alone document (man, html, etc).

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

3 files changed, 810 insertions, 781 deletions

diff --git a/Makefile b/Makefile
index 2be61fcf1c..cee6e28659 100644
--- a/Makefile
+++ b/Makefile
@@ -209,6 +209,7 @@ ifdef BUILD_DOCS
 DOCS=qemu-doc.html qemu-doc.txt qemu.1 qemu-img.1 qemu-nbd.8 qemu-ga.8
 DOCS+=docs/interop/qemu-qmp-ref.html docs/interop/qemu-qmp-ref.txt docs/interop/qemu-qmp-ref.7
 DOCS+=docs/interop/qemu-ga-ref.html docs/interop/qemu-ga-ref.txt docs/interop/qemu-ga-ref.7
+DOCS+=docs/qemu-block-drivers.7
 ifdef CONFIG_VIRTFS
 DOCS+=fsdev/virtfs-proxy-helper.1
 endif
@@ -532,6 +533,7 @@ distclean: clean
 	rm -f docs/interop/qemu-qmp-ref.txt docs/interop/qemu-ga-ref.txt
 	rm -f docs/interop/qemu-qmp-ref.pdf docs/interop/qemu-ga-ref.pdf
 	rm -f docs/interop/qemu-qmp-ref.html docs/interop/qemu-ga-ref.html
+	rm -f docs/qemu-block-drivers.7
 	for d in $(TARGET_DIRS); do \
 	rm -rf $$d || exit 1 ; \
         done
@@ -576,6 +578,7 @@ ifdef CONFIG_POSIX
 	$(INSTALL_DATA) qemu.1 "$(DESTDIR)$(mandir)/man1"
 	$(INSTALL_DIR) "$(DESTDIR)$(mandir)/man7"
 	$(INSTALL_DATA) docs/interop/qemu-qmp-ref.7 "$(DESTDIR)$(mandir)/man7"
+	$(INSTALL_DATA) docs/qemu-block-drivers.7 "$(DESTDIR)$(mandir)/man7"
 ifneq ($(TOOLS),)
 	$(INSTALL_DATA) qemu-img.1 "$(DESTDIR)$(mandir)/man1"
 	$(INSTALL_DIR) "$(DESTDIR)$(mandir)/man8"
@@ -721,6 +724,7 @@ qemu-img.1: qemu-img.texi qemu-option-trace.texi qemu-img-cmds.texi
 fsdev/virtfs-proxy-helper.1: fsdev/virtfs-proxy-helper.texi
 qemu-nbd.8: qemu-nbd.texi qemu-option-trace.texi
 qemu-ga.8: qemu-ga.texi
+docs/qemu-block-drivers.7: docs/qemu-block-drivers.texi
 
 html: qemu-doc.html docs/interop/qemu-qmp-ref.html docs/interop/qemu-ga-ref.html
 info: qemu-doc.info docs/interop/qemu-qmp-ref.info docs/interop/qemu-ga-ref.info
@@ -730,7 +734,7 @@ txt: qemu-doc.txt docs/interop/qemu-qmp-ref.txt docs/interop/qemu-ga-ref.txt
 qemu-doc.html qemu-doc.info qemu-doc.pdf qemu-doc.txt: \
 	qemu-img.texi qemu-nbd.texi qemu-options.texi qemu-option-trace.texi \
 	qemu-monitor.texi qemu-img-cmds.texi qemu-ga.texi \
-	qemu-monitor-info.texi
+	qemu-monitor-info.texi docs/qemu-block-drivers.texi
 
 docs/interop/qemu-ga-ref.dvi docs/interop/qemu-ga-ref.html \
     docs/interop/qemu-ga-ref.info docs/interop/qemu-ga-ref.pdf \
diff --git a/docs/qemu-block-drivers.texi b/docs/qemu-block-drivers.texi
new file mode 100644
index 0000000000..1cb1e55686
--- /dev/null
+++ b/docs/qemu-block-drivers.texi
@@ -0,0 +1,804 @@
+@c man begin SYNOPSIS
+QEMU block driver reference manual
+@c man end
+
+@c man begin DESCRIPTION
+
+@node disk_images_formats
+@subsection Disk image file formats
+
+QEMU supports many image file formats that can be used with VMs as well as with
+any of the tools (like @code{qemu-img}). This includes the preferred formats
+raw and qcow2 as well as formats that are supported for compatibility with
+older QEMU versions or other hypervisors.
+
+Depending on the image format, different options can be passed to
+@code{qemu-img create} and @code{qemu-img convert} using the @code{-o} option.
+This section describes each format and the options that are supported for it.
+
+@table @option
+@item raw
+
+Raw disk image format. This format has the advantage of
+being simple and easily exportable to all other emulators. If your
+file system supports @emph{holes} (for example in ext2 or ext3 on
+Linux or NTFS on Windows), then only the written sectors will reserve
+space. Use @code{qemu-img info} to know the real size used by the
+image or @code{ls -ls} on Unix/Linux.
+
+Supported options:
+@table @code
+@item preallocation
+Preallocation mode (allowed values: @code{off}, @code{falloc}, @code{full}).
+@code{falloc} mode preallocates space for image by calling posix_fallocate().
+@code{full} mode preallocates space for image by writing zeros to underlying
+storage.
+@end table
+
+@item qcow2
+QEMU image format, the most versatile format. Use it to have smaller
+images (useful if your filesystem does not supports holes, for example
+on Windows), zlib based compression and support of multiple VM
+snapshots.
+
+Supported options:
+@table @code
+@item compat
+Determines the qcow2 version to use. @code{compat=0.10} uses the
+traditional image format that can be read by any QEMU since 0.10.
+@code{compat=1.1} enables image format extensions that only QEMU 1.1 and
+newer understand (this is the default). Amongst others, this includes
+zero clusters, which allow efficient copy-on-read for sparse images.
+
+@item backing_file
+File name of a base image (see @option{create} subcommand)
+@item backing_fmt
+Image format of the base image
+@item encryption
+This option is deprecated and equivalent to @code{encrypt.format=aes}
+
+@item encrypt.format
+
+If this is set to @code{luks}, it requests that the qcow2 payload (not
+qcow2 header) be encrypted using the LUKS format. The passphrase to
+use to unlock the LUKS key slot is given by the @code{encrypt.key-secret}
+parameter. LUKS encryption parameters can be tuned with the other
+@code{encrypt.*} parameters.
+
+If this is set to @code{aes}, the image is encrypted with 128-bit AES-CBC.
+The encryption key is given by the @code{encrypt.key-secret} parameter.
+This encryption format is considered to be flawed by modern cryptography
+standards, suffering from a number of design problems:
+
+@itemize @minus
+@item The AES-CBC cipher is used with predictable initialization vectors based
+on the sector number. This makes it vulnerable to chosen plaintext attacks
+which can reveal the existence of encrypted data.
+@item The user passphrase is directly used as the encryption key. A poorly
+chosen or short passphrase will compromise the security of the encryption.
+@item In the event of the passphrase being compromised there is no way to
+change the passphrase to protect data in any qcow images. The files must
+be cloned, using a different encryption passphrase in the new file. The
+original file must then be securely erased using a program like shred,
+though even this is ineffective with many modern storage technologies.
+@end itemize
+
+The use of this is no longer supported in system emulators. Support only
+remains in the command line utilities, for the purposes of data liberation
+and interoperability with old versions of QEMU. The @code{luks} format
+should be used instead.
+
+@item encrypt.key-secret
+
+Provides the ID of a @code{secret} object that contains the passphrase
+(@code{encrypt.format=luks}) or encryption key (@code{encrypt.format=aes}).
+
+@item encrypt.cipher-alg
+
+Name of the cipher algorithm and key length. Currently defaults
+to @code{aes-256}. Only used when @code{encrypt.format=luks}.
+
+@item encrypt.cipher-mode
+
+Name of the encryption mode to use. Currently defaults to @code{xts}.
+Only used when @code{encrypt.format=luks}.
+
+@item encrypt.ivgen-alg
+
+Name of the initialization vector generator algorithm. Currently defaults
+to @code{plain64}. Only used when @code{encrypt.format=luks}.
+
+@item encrypt.ivgen-hash-alg
+
+Name of the hash algorithm to use with the initialization vector generator
+(if required). Defaults to @code{sha256}. Only used when @code{encrypt.format=luks}.
+
+@item encrypt.hash-alg
+
+Name of the hash algorithm to use for PBKDF algorithm
+Defaults to @code{sha256}. Only used when @code{encrypt.format=luks}.
+
+@item encrypt.iter-time
+
+Amount of time, in milliseconds, to use for PBKDF algorithm per key slot.
+Defaults to @code{2000}. Only used when @code{encrypt.format=luks}.
+
+@item cluster_size
+Changes the qcow2 cluster size (must be between 512 and 2M). Smaller cluster
+sizes can improve the image file size whereas larger cluster sizes generally
+provide better performance.
+
+@item preallocation
+Preallocation mode (allowed values: @code{off}, @code{metadata}, @code{falloc},
+@code{full}). An image with preallocated metadata is initially larger but can
+improve performance when the image needs to grow. @code{falloc} and @code{full}
+preallocations are like the same options of @code{raw} format, but sets up
+metadata also.
+
+@item lazy_refcounts
+If this option is set to @code{on}, reference count updates are postponed with
+the goal of avoiding metadata I/O and improving performance. This is
+particularly interesting with @option{cache=writethrough} which doesn't batch
+metadata updates. The tradeoff is that after a host crash, the reference count
+tables must be rebuilt, i.e. on the next open an (automatic) @code{qemu-img
+check -r all} is required, which may take some time.
+
+This option can only be enabled if @code{compat=1.1} is specified.
+
+@item nocow
+If this option is set to @code{on}, it will turn off COW of the file. It's only
+valid on btrfs, no effect on other file systems.
+
+Btrfs has low performance when hosting a VM image file, even more when the guest
+on the VM also using btrfs as file system. Turning off COW is a way to mitigate
+this bad performance. Generally there are two ways to turn off COW on btrfs:
+a) Disable it by mounting with nodatacow, then all newly created files will be
+NOCOW. b) For an empty file, add the NOCOW file attribute. That's what this option
+does.
+
+Note: this option is only valid to new or empty files. If there is an existing
+file which is COW and has data blocks already, it couldn't be changed to NOCOW
+by setting @code{nocow=on}. One can issue @code{lsattr filename} to check if
+the NOCOW flag is set or not (Capital 'C' is NOCOW flag).
+
+@end table
+
+@item qed
+Old QEMU image format with support for backing files and compact image files
+(when your filesystem or transport medium does not support holes).
+
+When converting QED images to qcow2, you might want to consider using the
+@code{lazy_refcounts=on} option to get a more QED-like behaviour.
+
+Supported options:
+@table @code
+@item backing_file
+File name of a base image (see @option{create} subcommand).
+@item backing_fmt
+Image file format of backing file (optional).  Useful if the format cannot be
+autodetected because it has no header, like some vhd/vpc files.
+@item cluster_size
+Changes the cluster size (must be power-of-2 between 4K and 64K). Smaller
+cluster sizes can improve the image file size whereas larger cluster sizes
+generally provide better performance.
+@item table_size
+Changes the number of clusters per L1/L2 table (must be power-of-2 between 1
+and 16).  There is normally no need to change this value but this option can be
+used for performance benchmarking.
+@end table
+
+@item qcow
+Old QEMU image format with support for backing files, compact image files,
+encryption and compression.
+
+Supported options:
+@table @code
+@item backing_file
+File name of a base image (see @option{create} subcommand)
+@item encryption
+This option is deprecated and equivalent to @code{encrypt.format=aes}
+
+@item encrypt.format
+If this is set to @code{aes}, the image is encrypted with 128-bit AES-CBC.
+The encryption key is given by the @code{encrypt.key-secret} parameter.
+This encryption format is considered to be flawed by modern cryptography
+standards, suffering from a number of design problems enumerated previously
+against the @code{qcow2} image format.
+
+The use of this is no longer supported in system emulators. Support only
+remains in the command line utilities, for the purposes of data liberation
+and interoperability with old versions of QEMU.
+
+Users requiring native encryption should use the @code{qcow2} format
+instead with @code{encrypt.format=luks}.
+
+@item encrypt.key-secret
+
+Provides the ID of a @code{secret} object that contains the encryption
+key (@code{encrypt.format=aes}).
+
+@end table
+
+@item luks
+
+LUKS v1 encryption format, compatible with Linux dm-crypt/cryptsetup
+
+Supported options:
+@table @code
+
+@item key-secret
+
+Provides the ID of a @code{secret} object that contains the passphrase.
+
+@item cipher-alg
+
+Name of the cipher algorithm and key length. Currently defaults
+to @code{aes-256}.
+
+@item cipher-mode
+
+Name of the encryption mode to use. Currently defaults to @code{xts}.
+
+@item ivgen-alg
+
+Name of the initialization vector generator algorithm. Currently defaults
+to @code{plain64}.
+
+@item ivgen-hash-alg
+
+Name of the hash algorithm to use with the initialization vector generator
+(if required). Defaults to @code{sha256}.
+
+@item hash-alg
+
+Name of the hash algorithm to use for PBKDF algorithm
+Defaults to @code{sha256}.
+
+@item iter-time
+
+Amount of time, in milliseconds, to use for PBKDF algorithm per key slot.
+Defaults to @code{2000}.
+
+@end table
+
+@item vdi
+VirtualBox 1.1 compatible image format.
+Supported options:
+@table @code
+@item static
+If this option is set to @code{on}, the image is created with metadata
+preallocation.
+@end table
+
+@item vmdk
+VMware 3 and 4 compatible image format.
+
+Supported options:
+@table @code
+@item backing_file
+File name of a base image (see @option{create} subcommand).
+@item compat6
+Create a VMDK version 6 image (instead of version 4)
+@item hwversion
+Specify vmdk virtual hardware version. Compat6 flag cannot be enabled
+if hwversion is specified.
+@item subformat
+Specifies which VMDK subformat to use. Valid options are
+@code{monolithicSparse} (default),
+@code{monolithicFlat},
+@code{twoGbMaxExtentSparse},
+@code{twoGbMaxExtentFlat} and
+@code{streamOptimized}.
+@end table
+
+@item vpc
+VirtualPC compatible image format (VHD).
+Supported options:
+@table @code
+@item subformat
+Specifies which VHD subformat to use. Valid options are
+@code{dynamic} (default) and @code{fixed}.
+@end table
+
+@item VHDX
+Hyper-V compatible image format (VHDX).
+Supported options:
+@table @code
+@item subformat
+Specifies which VHDX subformat to use. Valid options are
+@code{dynamic} (default) and @code{fixed}.
+@item block_state_zero
+Force use of payload blocks of type 'ZERO'.  Can be set to @code{on} (default)
+or @code{off}.  When set to @code{off}, new blocks will be created as
+@code{PAYLOAD_BLOCK_NOT_PRESENT}, which means parsers are free to return
+arbitrary data for those blocks.  Do not set to @code{off} when using
+@code{qemu-img convert} with @code{subformat=dynamic}.
+@item block_size
+Block size; min 1 MB, max 256 MB.  0 means auto-calculate based on image size.
+@item log_size
+Log size; min 1 MB.
+@end table
+@end table
+
+@subsubsection Read-only formats
+More disk image file formats are supported in a read-only mode.
+@table @option
+@item bochs
+Bochs images of @code{growing} type.
+@item cloop
+Linux Compressed Loop image, useful only to reuse directly compressed
+CD-ROM images present for example in the Knoppix CD-ROMs.
+@item dmg
+Apple disk image.
+@item parallels
+Parallels disk image format.
+@end table
+
+
+@node host_drives
+@subsection Using host drives
+
+In addition to disk image files, QEMU can directly access host
+devices. We describe here the usage for QEMU version >= 0.8.3.
+
+@subsubsection Linux
+
+On Linux, you can directly use the host device filename instead of a
+disk image filename provided you have enough privileges to access
+it. For example, use @file{/dev/cdrom} to access to the CDROM.
+
+@table @code
+@item CD
+You can specify a CDROM device even if no CDROM is loaded. QEMU has
+specific code to detect CDROM insertion or removal. CDROM ejection by
+the guest OS is supported. Currently only data CDs are supported.
+@item Floppy
+You can specify a floppy device even if no floppy is loaded. Floppy
+removal is currently not detected accurately (if you change floppy
+without doing floppy access while the floppy is not loaded, the guest
+OS will think that the same floppy is loaded).
+Use of the host's floppy device is deprecated, and support for it will
+be removed in a future release.
+@item Hard disks
+Hard disks can be used. Normally you must specify the whole disk
+(@file{/dev/hdb} instead of @file{/dev/hdb1}) so that the guest OS can
+see it as a partitioned disk. WARNING: unless you know what you do, it
+is better to only make READ-ONLY accesses to the hard disk otherwise
+you may corrupt your host data (use the @option{-snapshot} command
+line option or modify the device permissions accordingly).
+@end table
+
+@subsubsection Windows
+
+@table @code
+@item CD
+The preferred syntax is the drive letter (e.g. @file{d:}). The
+alternate syntax @file{\\.\d:} is supported. @file{/dev/cdrom} is
+supported as an alias to the first CDROM drive.
+
+Currently there is no specific code to handle removable media, so it
+is better to use the @code{change} or @code{eject} monitor commands to
+change or eject media.
+@item Hard disks
+Hard disks can be used with the syntax: @file{\\.\PhysicalDrive@var{N}}
+where @var{N} is the drive number (0 is the first hard disk).
+
+WARNING: unless you know what you do, it is better to only make
+READ-ONLY accesses to the hard disk otherwise you may corrupt your
+host data (use the @option{-snapshot} command line so that the
+modifications are written in a temporary file).
+@end table
+
+
+@subsubsection Mac OS X
+
+@file{/dev/cdrom} is an alias to the first CDROM.
+
+Currently there is no specific code to handle removable media, so it
+is better to use the @code{change} or @code{eject} monitor commands to
+change or eject media.
+
+@node disk_images_fat_images
+@subsection Virtual FAT disk images
+
+QEMU can automatically create a virtual FAT disk image from a
+directory tree. In order to use it, just type:
+
+@example
+qemu-system-i386 linux.img -hdb fat:/my_directory
+@end example
+
+Then you access access to all the files in the @file{/my_directory}
+directory without having to copy them in a disk image or to export
+them via SAMBA or NFS. The default access is @emph{read-only}.
+
+Floppies can be emulated with the @code{:floppy:} option:
+
+@example
+qemu-system-i386 linux.img -fda fat:floppy:/my_directory
+@end example
+
+A read/write support is available for testing (beta stage) with the
+@code{:rw:} option:
+
+@example
+qemu-system-i386 linux.img -fda fat:floppy:rw:/my_directory
+@end example
+
+What you should @emph{never} do:
+@itemize
+@item use non-ASCII filenames ;
+@item use "-snapshot" together with ":rw:" ;
+@item expect it to work when loadvm'ing ;
+@item write to the FAT directory on the host system while accessing it with the guest system.
+@end itemize
+
+@node disk_images_nbd
+@subsection NBD access
+
+QEMU can access directly to block device exported using the Network Block Device
+protocol.
+
+@example
+qemu-system-i386 linux.img -hdb nbd://my_nbd_server.mydomain.org:1024/
+@end example
+
+If the NBD server is located on the same host, you can use an unix socket instead
+of an inet socket:
+
+@example
+qemu-system-i386 linux.img -hdb nbd+unix://?socket=/tmp/my_socket
+@end example
+
+In this case, the block device must be exported using qemu-nbd:
+
+@example
+qemu-nbd --socket=/tmp/my_socket my_disk.qcow2
+@end example
+
+The use of qemu-nbd allows sharing of a disk between several guests:
+@example
+qemu-nbd --socket=/tmp/my_socket --share=2 my_disk.qcow2
+@end example
+
+@noindent
+and then you can use it with two guests:
+@example
+qemu-system-i386 linux1.img -hdb nbd+unix://?socket=/tmp/my_socket
+qemu-system-i386 linux2.img -hdb nbd+unix://?socket=/tmp/my_socket
+@end example
+
+If the nbd-server uses named exports (supported since NBD 2.9.18, or with QEMU's
+own embedded NBD server), you must specify an export name in the URI:
+@example
+qemu-system-i386 -cdrom nbd://localhost/debian-500-ppc-netinst
+qemu-system-i386 -cdrom nbd://localhost/openSUSE-11.1-ppc-netinst
+@end example
+
+The URI syntax for NBD is supported since QEMU 1.3.  An alternative syntax is
+also available.  Here are some example of the older syntax:
+@example
+qemu-system-i386 linux.img -hdb nbd:my_nbd_server.mydomain.org:1024
+qemu-system-i386 linux2.img -hdb nbd:unix:/tmp/my_socket
+qemu-system-i386 -cdrom nbd:localhost:10809:exportname=debian-500-ppc-netinst
+@end example
+
+@node disk_images_sheepdog
+@subsection Sheepdog disk images
+
+Sheepdog is a distributed storage system for QEMU.  It provides highly
+available block level storage volumes that can be attached to
+QEMU-based virtual machines.
+
+You can create a Sheepdog disk image with the command:
+@example
+qemu-img create sheepdog:///@var{image} @var{size}
+@end example
+where @var{image} is the Sheepdog image name and @var{size} is its
+size.
+
+To import the existing @var{filename} to Sheepdog, you can use a
+convert command.
+@example
+qemu-img convert @var{filename} sheepdog:///@var{image}
+@end example
+
+You can boot from the Sheepdog disk image with the command:
+@example
+qemu-system-i386 sheepdog:///@var{image}
+@end example
+
+You can also create a snapshot of the Sheepdog image like qcow2.
+@example
+qemu-img snapshot -c @var{tag} sheepdog:///@var{image}
+@end example
+where @var{tag} is a tag name of the newly created snapshot.
+
+To boot from the Sheepdog snapshot, specify the tag name of the
+snapshot.
+@example
+qemu-system-i386 sheepdog:///@var{image}#@var{tag}
+@end example
+
+You can create a cloned image from the existing snapshot.
+@example
+qemu-img create -b sheepdog:///@var{base}#@var{tag} sheepdog:///@var{image}
+@end example
+where @var{base} is a image name of the source snapshot and @var{tag}
+is its tag name.
+
+You can use an unix socket instead of an inet socket:
+
+@example
+qemu-system-i386 sheepdog+unix:///@var{image}?socket=@var{path}
+@end example
+
+If the Sheepdog daemon doesn't run on the local host, you need to
+specify one of the Sheepdog servers to connect to.
+@example
+qemu-img create sheepdog://@var{hostname}:@var{port}/@var{image} @var{size}
+qemu-system-i386 sheepdog://@var{hostname}:@var{port}/@var{image}
+@end example
+
+@node disk_images_iscsi
+@subsection iSCSI LUNs
+
+iSCSI is a popular protocol used to access SCSI devices across a computer
+network.
+
+There are two different ways iSCSI devices can be used by QEMU.
+
+The first method is to mount the iSCSI LUN on the host, and make it appear as
+any other ordinary SCSI device on the host and then to access this device as a
+/dev/sd device from QEMU. How to do this differs between host OSes.
+
+The second method involves using the iSCSI initiator that is built into
+QEMU. This provides a mechanism that works the same way regardless of which
+host OS you are running QEMU on. This section will describe this second method
+of using iSCSI together with QEMU.
+
+In QEMU, iSCSI devices are described using special iSCSI URLs
+
+@example
+URL syntax:
+iscsi://[<username>[%<password>]@@]<host>[:<port>]/<target-iqn-name>/<lun>
+@end example
+
+Username and password are optional and only used if your target is set up
+using CHAP authentication for access control.
+Alternatively the username and password can also be set via environment
+variables to have these not show up in the process list
+
+@example
+export LIBISCSI_CHAP_USERNAME=<username>
+export LIBISCSI_CHAP_PASSWORD=<password>
+iscsi://<host>/<target-iqn-name>/<lun>
+@end example
+
+Various session related parameters can be set via special options, either
+in a configuration file provided via '-readconfig' or directly on the
+command line.
+
+If the initiator-name is not specified qemu will use a default name
+of 'iqn.2008-11.org.linux-kvm[:<uuid>'] where <uuid> is the UUID of the
+virtual machine. If the UUID is not specified qemu will use
+'iqn.2008-11.org.linux-kvm[:<name>'] where <name> is the name of the
+virtual machine.
+
+@example
+Setting a specific initiator name to use when logging in to the target
+-iscsi initiator-name=iqn.qemu.test:my-initiator
+@end example
+
+@example
+Controlling which type of header digest to negotiate with the target
+-iscsi header-digest=CRC32C|CRC32C-NONE|NONE-CRC32C|NONE
+@end example
+
+These can also be set via a configuration file
+@example
+[iscsi]
+  user = "CHAP username"
+  password = "CHAP password"
+  initiator-name = "iqn.qemu.test:my-initiator"
+  # header digest is one of CRC32C|CRC32C-NONE|NONE-CRC32C|NONE
+  header-digest = "CRC32C"
+@end example
+
+
+Setting the target name allows different options for different targets
+@example
+[iscsi "iqn.target.name"]
+  user = "CHAP username"
+  password = "CHAP password"
+  initiator-name = "iqn.qemu.test:my-initiator"
+  # header digest is one of CRC32C|CRC32C-NONE|NONE-CRC32C|NONE
+  header-digest = "CRC32C"
+@end example
+
+
+Howto use a configuration file to set iSCSI configuration options:
+@example
+cat >iscsi.conf <<EOF
+[iscsi]
+  user = "me"
+  password = "my password"
+  initiator-name = "iqn.qemu.test:my-initiator"
+  header-digest = "CRC32C"
+EOF
+
+qemu-system-i386 -drive file=iscsi://127.0.0.1/iqn.qemu.test/1 \
+    -readconfig iscsi.conf
+@end example
+
+
+Howto set up a simple iSCSI target on loopback and accessing it via QEMU:
+@example
+This example shows how to set up an iSCSI target with one CDROM and one DISK
+using the Linux STGT software target. This target is available on Red Hat based
+systems as the package 'scsi-target-utils'.
+
+tgtd --iscsi portal=127.0.0.1:3260
+tgtadm --lld iscsi --op new --mode target --tid 1 -T iqn.qemu.test
+tgtadm --lld iscsi --mode logicalunit --op new --tid 1 --lun 1 \
+    -b /IMAGES/disk.img --device-type=disk
+tgtadm --lld iscsi --mode logicalunit --op new --tid 1 --lun 2 \
+    -b /IMAGES/cd.iso --device-type=cd
+tgtadm --lld iscsi --op bind --mode target --tid 1 -I ALL
+
+qemu-system-i386 -iscsi initiator-name=iqn.qemu.test:my-initiator \
+    -boot d -drive file=iscsi://127.0.0.1/iqn.qemu.test/1 \
+    -cdrom iscsi://127.0.0.1/iqn.qemu.test/2
+@end example
+
+@node disk_images_gluster
+@subsection GlusterFS disk images
+
+GlusterFS is a user space distributed file system.
+
+You can boot from the GlusterFS disk image with the command:
+@example
+URI:
+qemu-system-x86_64 -drive file=gluster[+@var{type}]://[@var{host}[:@var{port}]]/@var{volume}/@var{path}
+                               [?socket=...][,file.debug=9][,file.logfile=...]
+
+JSON:
+qemu-system-x86_64 'json:@{"driver":"qcow2",
+                           "file":@{"driver":"gluster",
+                                    "volume":"testvol","path":"a.img","debug":9,"logfile":"...",
+                                    "server":[@{"type":"tcp","host":"...","port":"..."@},
+                                              @{"type":"unix","socket":"..."@}]@}@}'
+@end example
+
+@var{gluster} is the protocol.
+
+@var{type} specifies the transport type used to connect to gluster
+management daemon (glusterd). Valid transport types are
+tcp and unix. In the URI form, if a transport type isn't specified,
+then tcp type is assumed.
+
+@var{host} specifies the server where the volume file specification for
+the given volume resides. This can be either a hostname or an ipv4 address.
+If transport type is unix, then @var{host} field should not be specified.
+Instead @var{socket} field needs to be populated with the path to unix domain
+socket.
+
+@var{port} is the port number on which glusterd is listening. This is optional
+and if not specified, it defaults to port 24007. If the transport type is unix,
+then @var{port} should not be specified.
+
+@var{volume} is the name of the gluster volume which contains the disk image.
+
+@var{path} is the path to the actual disk image that resides on gluster volume.
+
+@var{debug} is the logging level of the gluster protocol driver. Debug levels
+are 0-9, with 9 being the most verbose, and 0 representing no debugging output.
+The default level is 4. The current logging levels defined in the gluster source
+are 0 - None, 1 - Emergency, 2 - Alert, 3 - Critical, 4 - Error, 5 - Warning,
+6 - Notice, 7 - Info, 8 - Debug, 9 - Trace
+
+@var{logfile} is a commandline option to mention log file path which helps in
+logging to the specified file and also help in persisting the gfapi logs. The
+default is stderr.
+
+
+
+
+You can create a GlusterFS disk image with the command:
+@example
+qemu-img create gluster://@var{host}/@var{volume}/@var{path} @var{size}
+@end example
+
+Examples
+@example
+qemu-system-x86_64 -drive file=gluster://1.2.3.4/testvol/a.img
+qemu-system-x86_64 -drive file=gluster+tcp://1.2.3.4/testvol/a.img
+qemu-system-x86_64 -drive file=gluster+tcp://1.2.3.4:24007/testvol/dir/a.img
+qemu-system-x86_64 -drive file=gluster+tcp://[1:2:3:4:5:6:7:8]/testvol/dir/a.img
+qemu-system-x86_64 -drive file=gluster+tcp://[1:2:3:4:5:6:7:8]:24007/testvol/dir/a.img
+qemu-system-x86_64 -drive file=gluster+tcp://server.domain.com:24007/testvol/dir/a.img
+qemu-system-x86_64 -drive file=gluster+unix:///testvol/dir/a.img?socket=/tmp/glusterd.socket
+qemu-system-x86_64 -drive file=gluster+rdma://1.2.3.4:24007/testvol/a.img
+qemu-system-x86_64 -drive file=gluster://1.2.3.4/testvol/a.img,file.debug=9,file.logfile=/var/log/qemu-gluster.log
+qemu-system-x86_64 'json:@{"driver":"qcow2",
+                           "file":@{"driver":"gluster",
+                                    "volume":"testvol","path":"a.img",
+                                    "debug":9,"logfile":"/var/log/qemu-gluster.log",
+                                    "server":[@{"type":"tcp","host":"1.2.3.4","port":24007@},
+                                              @{"type":"unix","socket":"/var/run/glusterd.socket"@}]@}@}'
+qemu-system-x86_64 -drive driver=qcow2,file.driver=gluster,file.volume=testvol,file.path=/path/a.img,
+                                       file.debug=9,file.logfile=/var/log/qemu-gluster.log,
+                                       file.server.0.type=tcp,file.server.0.host=1.2.3.4,file.server.0.port=24007,
+                                       file.server.1.type=unix,file.server.1.socket=/var/run/glusterd.socket
+@end example
+
+@node disk_images_ssh
+@subsection Secure Shell (ssh) disk images
+
+You can access disk images located on a remote ssh server
+by using the ssh protocol:
+
+@example
+qemu-system-x86_64 -drive file=ssh://[@var{user}@@]@var{server}[:@var{port}]/@var{path}[?host_key_check=@var{host_key_check}]
+@end example
+
+Alternative syntax using properties:
+
+@example
+qemu-system-x86_64 -drive file.driver=ssh[,file.user=@var{user}],file.host=@var{server}[,file.port=@var{port}],file.path=@var{path}[,file.host_key_check=@var{host_key_check}]
+@end example
+
+@var{ssh} is the protocol.
+
+@var{user} is the remote user.  If not specified, then the local
+username is tried.
+
+@var{server} specifies the remote ssh server.  Any ssh server can be
+used, but it must implement the sftp-server protocol.  Most Unix/Linux
+systems should work without requiring any extra configuration.
+
+@var{port} is the port number on which sshd is listening.  By default
+the standard ssh port (22) is used.
+
+@var{path} is the path to the disk image.
+
+The optional @var{host_key_check} parameter controls how the remote
+host's key is checked.  The default is @code{yes} which means to use
+the local @file{.ssh/known_hosts} file.  Setting this to @code{no}
+turns off known-hosts checking.  Or you can check that the host key
+matches a specific fingerprint:
+@code{host_key_check=md5:78:45:8e:14:57:4f:d5:45:83:0a:0e:f3:49:82:c9:c8}
+(@code{sha1:} can also be used as a prefix, but note that OpenSSH
+tools only use MD5 to print fingerprints).
+
+Currently authentication must be done using ssh-agent.  Other
+authentication methods may be supported in future.
+
+Note: Many ssh servers do not support an @code{fsync}-style operation.
+The ssh driver cannot guarantee that disk flush requests are
+obeyed, and this causes a risk of disk corruption if the remote
+server or network goes down during writes.  The driver will
+print a warning when @code{fsync} is not supported:
+
+warning: ssh server @code{ssh.example.com:22} does not support fsync
+
+With sufficiently new versions of libssh2 and OpenSSH, @code{fsync} is
+supported.
+
+@c man end
+
+@ignore
+
+@setfilename qemu-block-drivers
+@settitle QEMU block drivers reference
+
+@c man begin SEEALSO
+The HTML documentation of QEMU for more precise information and Linux
+user mode emulator invocation.
+@c man end
+
+@c man begin AUTHOR
+Fabrice Bellard and the QEMU Project developers
+@c man end
+
+@end ignore
diff --git a/qemu-doc.texi b/qemu-doc.texi
index 4076226f39..ecd186a159 100644
--- a/qemu-doc.texi
+++ b/qemu-doc.texi
@@ -490,786 +490,7 @@ state is not saved or restored properly (in particular USB).
 
 @include qemu-nbd.texi
 
-@node disk_images_formats
-@subsection Disk image file formats
-
-QEMU supports many image file formats that can be used with VMs as well as with
-any of the tools (like @code{qemu-img}). This includes the preferred formats
-raw and qcow2 as well as formats that are supported for compatibility with
-older QEMU versions or other hypervisors.
-
-Depending on the image format, different options can be passed to
-@code{qemu-img create} and @code{qemu-img convert} using the @code{-o} option.
-This section describes each format and the options that are supported for it.
-
-@table @option
-@item raw
-
-Raw disk image format. This format has the advantage of
-being simple and easily exportable to all other emulators. If your
-file system supports @emph{holes} (for example in ext2 or ext3 on
-Linux or NTFS on Windows), then only the written sectors will reserve
-space. Use @code{qemu-img info} to know the real size used by the
-image or @code{ls -ls} on Unix/Linux.
-
-Supported options:
-@table @code
-@item preallocation
-Preallocation mode (allowed values: @code{off}, @code{falloc}, @code{full}).
-@code{falloc} mode preallocates space for image by calling posix_fallocate().
-@code{full} mode preallocates space for image by writing zeros to underlying
-storage.
-@end table
-
-@item qcow2
-QEMU image format, the most versatile format. Use it to have smaller
-images (useful if your filesystem does not supports holes, for example
-on Windows), zlib based compression and support of multiple VM
-snapshots.
-
-Supported options:
-@table @code
-@item compat
-Determines the qcow2 version to use. @code{compat=0.10} uses the
-traditional image format that can be read by any QEMU since 0.10.
-@code{compat=1.1} enables image format extensions that only QEMU 1.1 and
-newer understand (this is the default). Amongst others, this includes
-zero clusters, which allow efficient copy-on-read for sparse images.
-
-@item backing_file
-File name of a base image (see @option{create} subcommand)
-@item backing_fmt
-Image format of the base image
-@item encryption
-This option is deprecated and equivalent to @code{encrypt.format=aes}
-
-@item encrypt.format
-
-If this is set to @code{luks}, it requests that the qcow2 payload (not
-qcow2 header) be encrypted using the LUKS format. The passphrase to
-use to unlock the LUKS key slot is given by the @code{encrypt.key-secret}
-parameter. LUKS encryption parameters can be tuned with the other
-@code{encrypt.*} parameters.
-
-If this is set to @code{aes}, the image is encrypted with 128-bit AES-CBC.
-The encryption key is given by the @code{encrypt.key-secret} parameter.
-This encryption format is considered to be flawed by modern cryptography
-standards, suffering from a number of design problems:
-
-@itemize @minus
-@item The AES-CBC cipher is used with predictable initialization vectors based
-on the sector number. This makes it vulnerable to chosen plaintext attacks
-which can reveal the existence of encrypted data.
-@item The user passphrase is directly used as the encryption key. A poorly
-chosen or short passphrase will compromise the security of the encryption.
-@item In the event of the passphrase being compromised there is no way to
-change the passphrase to protect data in any qcow images. The files must
-be cloned, using a different encryption passphrase in the new file. The
-original file must then be securely erased using a program like shred,
-though even this is ineffective with many modern storage technologies.
-@end itemize
-
-The use of this is no longer supported in system emulators. Support only
-remains in the command line utilities, for the purposes of data liberation
-and interoperability with old versions of QEMU. The @code{luks} format
-should be used instead.
-
-@item encrypt.key-secret
-
-Provides the ID of a @code{secret} object that contains the passphrase
-(@code{encrypt.format=luks}) or encryption key (@code{encrypt.format=aes}).
-
-@item encrypt.cipher-alg
-
-Name of the cipher algorithm and key length. Currently defaults
-to @code{aes-256}. Only used when @code{encrypt.format=luks}.
-
-@item encrypt.cipher-mode
-
-Name of the encryption mode to use. Currently defaults to @code{xts}.
-Only used when @code{encrypt.format=luks}.
-
-@item encrypt.ivgen-alg
-
-Name of the initialization vector generator algorithm. Currently defaults
-to @code{plain64}. Only used when @code{encrypt.format=luks}.
-
-@item encrypt.ivgen-hash-alg
-
-Name of the hash algorithm to use with the initialization vector generator
-(if required). Defaults to @code{sha256}. Only used when @code{encrypt.format=luks}.
-
-@item encrypt.hash-alg
-
-Name of the hash algorithm to use for PBKDF algorithm
-Defaults to @code{sha256}. Only used when @code{encrypt.format=luks}.
-
-@item encrypt.iter-time
-
-Amount of time, in milliseconds, to use for PBKDF algorithm per key slot.
-Defaults to @code{2000}. Only used when @code{encrypt.format=luks}.
-
-@item cluster_size
-Changes the qcow2 cluster size (must be between 512 and 2M). Smaller cluster
-sizes can improve the image file size whereas larger cluster sizes generally
-provide better performance.
-
-@item preallocation
-Preallocation mode (allowed values: @code{off}, @code{metadata}, @code{falloc},
-@code{full}). An image with preallocated metadata is initially larger but can
-improve performance when the image needs to grow. @code{falloc} and @code{full}
-preallocations are like the same options of @code{raw} format, but sets up
-metadata also.
-
-@item lazy_refcounts
-If this option is set to @code{on}, reference count updates are postponed with
-the goal of avoiding metadata I/O and improving performance. This is
-particularly interesting with @option{cache=writethrough} which doesn't batch
-metadata updates. The tradeoff is that after a host crash, the reference count
-tables must be rebuilt, i.e. on the next open an (automatic) @code{qemu-img
-check -r all} is required, which may take some time.
-
-This option can only be enabled if @code{compat=1.1} is specified.
-
-@item nocow
-If this option is set to @code{on}, it will turn off COW of the file. It's only
-valid on btrfs, no effect on other file systems.
-
-Btrfs has low performance when hosting a VM image file, even more when the guest
-on the VM also using btrfs as file system. Turning off COW is a way to mitigate
-this bad performance. Generally there are two ways to turn off COW on btrfs:
-a) Disable it by mounting with nodatacow, then all newly created files will be
-NOCOW. b) For an empty file, add the NOCOW file attribute. That's what this option
-does.
-
-Note: this option is only valid to new or empty files. If there is an existing
-file which is COW and has data blocks already, it couldn't be changed to NOCOW
-by setting @code{nocow=on}. One can issue @code{lsattr filename} to check if
-the NOCOW flag is set or not (Capital 'C' is NOCOW flag).
-
-@end table
-
-@item qed
-Old QEMU image format with support for backing files and compact image files
-(when your filesystem or transport medium does not support holes).
-
-When converting QED images to qcow2, you might want to consider using the
-@code{lazy_refcounts=on} option to get a more QED-like behaviour.
-
-Supported options:
-@table @code
-@item backing_file
-File name of a base image (see @option{create} subcommand).
-@item backing_fmt
-Image file format of backing file (optional).  Useful if the format cannot be
-autodetected because it has no header, like some vhd/vpc files.
-@item cluster_size
-Changes the cluster size (must be power-of-2 between 4K and 64K). Smaller
-cluster sizes can improve the image file size whereas larger cluster sizes
-generally provide better performance.
-@item table_size
-Changes the number of clusters per L1/L2 table (must be power-of-2 between 1
-and 16).  There is normally no need to change this value but this option can be
-used for performance benchmarking.
-@end table
-
-@item qcow
-Old QEMU image format with support for backing files, compact image files,
-encryption and compression.
-
-Supported options:
-@table @code
-@item backing_file
-File name of a base image (see @option{create} subcommand)
-@item encryption
-This option is deprecated and equivalent to @code{encrypt.format=aes}
-
-@item encrypt.format
-If this is set to @code{aes}, the image is encrypted with 128-bit AES-CBC.
-The encryption key is given by the @code{encrypt.key-secret} parameter.
-This encryption format is considered to be flawed by modern cryptography
-standards, suffering from a number of design problems enumerated previously
-against the @code{qcow2} image format.
-
-The use of this is no longer supported in system emulators. Support only
-remains in the command line utilities, for the purposes of data liberation
-and interoperability with old versions of QEMU.
-
-Users requiring native encryption should use the @code{qcow2} format
-instead with @code{encrypt.format=luks}.
-
-@item encrypt.key-secret
-
-Provides the ID of a @code{secret} object that contains the encryption
-key (@code{encrypt.format=aes}).
-
-@end table
-
-@item luks
-
-LUKS v1 encryption format, compatible with Linux dm-crypt/cryptsetup
-
-Supported options:
-@table @code
-
-@item key-secret
-
-Provides the ID of a @code{secret} object that contains the passphrase.
-
-@item cipher-alg
-
-Name of the cipher algorithm and key length. Currently defaults
-to @code{aes-256}.
-
-@item cipher-mode
-
-Name of the encryption mode to use. Currently defaults to @code{xts}.
-
-@item ivgen-alg
-
-Name of the initialization vector generator algorithm. Currently defaults
-to @code{plain64}.
-
-@item ivgen-hash-alg
-
-Name of the hash algorithm to use with the initialization vector generator
-(if required). Defaults to @code{sha256}.
-
-@item hash-alg
-
-Name of the hash algorithm to use for PBKDF algorithm
-Defaults to @code{sha256}.
-
-@item iter-time
-
-Amount of time, in milliseconds, to use for PBKDF algorithm per key slot.
-Defaults to @code{2000}.
-
-@end table
-
-@item vdi
-VirtualBox 1.1 compatible image format.
-Supported options:
-@table @code
-@item static
-If this option is set to @code{on}, the image is created with metadata
-preallocation.
-@end table
-
-@item vmdk
-VMware 3 and 4 compatible image format.
-
-Supported options:
-@table @code
-@item backing_file
-File name of a base image (see @option{create} subcommand).
-@item compat6
-Create a VMDK version 6 image (instead of version 4)
-@item hwversion
-Specify vmdk virtual hardware version. Compat6 flag cannot be enabled
-if hwversion is specified.
-@item subformat
-Specifies which VMDK subformat to use. Valid options are
-@code{monolithicSparse} (default),
-@code{monolithicFlat},
-@code{twoGbMaxExtentSparse},
-@code{twoGbMaxExtentFlat} and
-@code{streamOptimized}.
-@end table
-
-@item vpc
-VirtualPC compatible image format (VHD).
-Supported options:
-@table @code
-@item subformat
-Specifies which VHD subformat to use. Valid options are
-@code{dynamic} (default) and @code{fixed}.
-@end table
-
-@item VHDX
-Hyper-V compatible image format (VHDX).
-Supported options:
-@table @code
-@item subformat
-Specifies which VHDX subformat to use. Valid options are
-@code{dynamic} (default) and @code{fixed}.
-@item block_state_zero
-Force use of payload blocks of type 'ZERO'.  Can be set to @code{on} (default)
-or @code{off}.  When set to @code{off}, new blocks will be created as
-@code{PAYLOAD_BLOCK_NOT_PRESENT}, which means parsers are free to return
-arbitrary data for those blocks.  Do not set to @code{off} when using
-@code{qemu-img convert} with @code{subformat=dynamic}.
-@item block_size
-Block size; min 1 MB, max 256 MB.  0 means auto-calculate based on image size.
-@item log_size
-Log size; min 1 MB.
-@end table
-@end table
-
-@subsubsection Read-only formats
-More disk image file formats are supported in a read-only mode.
-@table @option
-@item bochs
-Bochs images of @code{growing} type.
-@item cloop
-Linux Compressed Loop image, useful only to reuse directly compressed
-CD-ROM images present for example in the Knoppix CD-ROMs.
-@item dmg
-Apple disk image.
-@item parallels
-Parallels disk image format.
-@end table
-
-
-@node host_drives
-@subsection Using host drives
-
-In addition to disk image files, QEMU can directly access host
-devices. We describe here the usage for QEMU version >= 0.8.3.
-
-@subsubsection Linux
-
-On Linux, you can directly use the host device filename instead of a
-disk image filename provided you have enough privileges to access
-it. For example, use @file{/dev/cdrom} to access to the CDROM.
-
-@table @code
-@item CD
-You can specify a CDROM device even if no CDROM is loaded. QEMU has
-specific code to detect CDROM insertion or removal. CDROM ejection by
-the guest OS is supported. Currently only data CDs are supported.
-@item Floppy
-You can specify a floppy device even if no floppy is loaded. Floppy
-removal is currently not detected accurately (if you change floppy
-without doing floppy access while the floppy is not loaded, the guest
-OS will think that the same floppy is loaded).
-Use of the host's floppy device is deprecated, and support for it will
-be removed in a future release.
-@item Hard disks
-Hard disks can be used. Normally you must specify the whole disk
-(@file{/dev/hdb} instead of @file{/dev/hdb1}) so that the guest OS can
-see it as a partitioned disk. WARNING: unless you know what you do, it
-is better to only make READ-ONLY accesses to the hard disk otherwise
-you may corrupt your host data (use the @option{-snapshot} command
-line option or modify the device permissions accordingly).
-@end table
-
-@subsubsection Windows
-
-@table @code
-@item CD
-The preferred syntax is the drive letter (e.g. @file{d:}). The
-alternate syntax @file{\\.\d:} is supported. @file{/dev/cdrom} is
-supported as an alias to the first CDROM drive.
-
-Currently there is no specific code to handle removable media, so it
-is better to use the @code{change} or @code{eject} monitor commands to
-change or eject media.
-@item Hard disks
-Hard disks can be used with the syntax: @file{\\.\PhysicalDrive@var{N}}
-where @var{N} is the drive number (0 is the first hard disk).
-
-WARNING: unless you know what you do, it is better to only make
-READ-ONLY accesses to the hard disk otherwise you may corrupt your
-host data (use the @option{-snapshot} command line so that the
-modifications are written in a temporary file).
-@end table
-
-
-@subsubsection Mac OS X
-
-@file{/dev/cdrom} is an alias to the first CDROM.
-
-Currently there is no specific code to handle removable media, so it
-is better to use the @code{change} or @code{eject} monitor commands to
-change or eject media.
-
-@node disk_images_fat_images
-@subsection Virtual FAT disk images
-
-QEMU can automatically create a virtual FAT disk image from a
-directory tree. In order to use it, just type:
-
-@example
-qemu-system-i386 linux.img -hdb fat:/my_directory
-@end example
-
-Then you access access to all the files in the @file{/my_directory}
-directory without having to copy them in a disk image or to export
-them via SAMBA or NFS. The default access is @emph{read-only}.
-
-Floppies can be emulated with the @code{:floppy:} option:
-
-@example
-qemu-system-i386 linux.img -fda fat:floppy:/my_directory
-@end example
-
-A read/write support is available for testing (beta stage) with the
-@code{:rw:} option:
-
-@example
-qemu-system-i386 linux.img -fda fat:floppy:rw:/my_directory
-@end example
-
-What you should @emph{never} do:
-@itemize
-@item use non-ASCII filenames ;
-@item use "-snapshot" together with ":rw:" ;
-@item expect it to work when loadvm'ing ;
-@item write to the FAT directory on the host system while accessing it with the guest system.
-@end itemize
-
-@node disk_images_nbd
-@subsection NBD access
-
-QEMU can access directly to block device exported using the Network Block Device
-protocol.
-
-@example
-qemu-system-i386 linux.img -hdb nbd://my_nbd_server.mydomain.org:1024/
-@end example
-
-If the NBD server is located on the same host, you can use an unix socket instead
-of an inet socket:
-
-@example
-qemu-system-i386 linux.img -hdb nbd+unix://?socket=/tmp/my_socket
-@end example
-
-In this case, the block device must be exported using qemu-nbd:
-
-@example
-qemu-nbd --socket=/tmp/my_socket my_disk.qcow2
-@end example
-
-The use of qemu-nbd allows sharing of a disk between several guests:
-@example
-qemu-nbd --socket=/tmp/my_socket --share=2 my_disk.qcow2
-@end example
-
-@noindent
-and then you can use it with two guests:
-@example
-qemu-system-i386 linux1.img -hdb nbd+unix://?socket=/tmp/my_socket
-qemu-system-i386 linux2.img -hdb nbd+unix://?socket=/tmp/my_socket
-@end example
-
-If the nbd-server uses named exports (supported since NBD 2.9.18, or with QEMU's
-own embedded NBD server), you must specify an export name in the URI:
-@example
-qemu-system-i386 -cdrom nbd://localhost/debian-500-ppc-netinst
-qemu-system-i386 -cdrom nbd://localhost/openSUSE-11.1-ppc-netinst
-@end example
-
-The URI syntax for NBD is supported since QEMU 1.3.  An alternative syntax is
-also available.  Here are some example of the older syntax:
-@example
-qemu-system-i386 linux.img -hdb nbd:my_nbd_server.mydomain.org:1024
-qemu-system-i386 linux2.img -hdb nbd:unix:/tmp/my_socket
-qemu-system-i386 -cdrom nbd:localhost:10809:exportname=debian-500-ppc-netinst
-@end example
-
-@node disk_images_sheepdog
-@subsection Sheepdog disk images
-
-Sheepdog is a distributed storage system for QEMU.  It provides highly
-available block level storage volumes that can be attached to
-QEMU-based virtual machines.
-
-You can create a Sheepdog disk image with the command:
-@example
-qemu-img create sheepdog:///@var{image} @var{size}
-@end example
-where @var{image} is the Sheepdog image name and @var{size} is its
-size.
-
-To import the existing @var{filename} to Sheepdog, you can use a
-convert command.
-@example
-qemu-img convert @var{filename} sheepdog:///@var{image}
-@end example
-
-You can boot from the Sheepdog disk image with the command:
-@example
-qemu-system-i386 sheepdog:///@var{image}
-@end example
-
-You can also create a snapshot of the Sheepdog image like qcow2.
-@example
-qemu-img snapshot -c @var{tag} sheepdog:///@var{image}
-@end example
-where @var{tag} is a tag name of the newly created snapshot.
-
-To boot from the Sheepdog snapshot, specify the tag name of the
-snapshot.
-@example
-qemu-system-i386 sheepdog:///@var{image}#@var{tag}
-@end example
-
-You can create a cloned image from the existing snapshot.
-@example
-qemu-img create -b sheepdog:///@var{base}#@var{tag} sheepdog:///@var{image}
-@end example
-where @var{base} is a image name of the source snapshot and @var{tag}
-is its tag name.
-
-You can use an unix socket instead of an inet socket:
-
-@example
-qemu-system-i386 sheepdog+unix:///@var{image}?socket=@var{path}
-@end example
-
-If the Sheepdog daemon doesn't run on the local host, you need to
-specify one of the Sheepdog servers to connect to.
-@example
-qemu-img create sheepdog://@var{hostname}:@var{port}/@var{image} @var{size}
-qemu-system-i386 sheepdog://@var{hostname}:@var{port}/@var{image}
-@end example
-
-@node disk_images_iscsi
-@subsection iSCSI LUNs
-
-iSCSI is a popular protocol used to access SCSI devices across a computer
-network.
-
-There are two different ways iSCSI devices can be used by QEMU.
-
-The first method is to mount the iSCSI LUN on the host, and make it appear as
-any other ordinary SCSI device on the host and then to access this device as a
-/dev/sd device from QEMU. How to do this differs between host OSes.
-
-The second method involves using the iSCSI initiator that is built into
-QEMU. This provides a mechanism that works the same way regardless of which
-host OS you are running QEMU on. This section will describe this second method
-of using iSCSI together with QEMU.
-
-In QEMU, iSCSI devices are described using special iSCSI URLs
-
-@example
-URL syntax:
-iscsi://[<username>[%<password>]@@]<host>[:<port>]/<target-iqn-name>/<lun>
-@end example
-
-Username and password are optional and only used if your target is set up
-using CHAP authentication for access control.
-Alternatively the username and password can also be set via environment
-variables to have these not show up in the process list
-
-@example
-export LIBISCSI_CHAP_USERNAME=<username>
-export LIBISCSI_CHAP_PASSWORD=<password>
-iscsi://<host>/<target-iqn-name>/<lun>
-@end example
-
-Various session related parameters can be set via special options, either
-in a configuration file provided via '-readconfig' or directly on the
-command line.
-
-If the initiator-name is not specified qemu will use a default name
-of 'iqn.2008-11.org.linux-kvm[:<uuid>'] where <uuid> is the UUID of the
-virtual machine. If the UUID is not specified qemu will use
-'iqn.2008-11.org.linux-kvm[:<name>'] where <name> is the name of the
-virtual machine.
-
-@example
-Setting a specific initiator name to use when logging in to the target
--iscsi initiator-name=iqn.qemu.test:my-initiator
-@end example
-
-@example
-Controlling which type of header digest to negotiate with the target
--iscsi header-digest=CRC32C|CRC32C-NONE|NONE-CRC32C|NONE
-@end example
-
-These can also be set via a configuration file
-@example
-[iscsi]
-  user = "CHAP username"
-  password = "CHAP password"
-  initiator-name = "iqn.qemu.test:my-initiator"
-  # header digest is one of CRC32C|CRC32C-NONE|NONE-CRC32C|NONE
-  header-digest = "CRC32C"
-@end example
-
-
-Setting the target name allows different options for different targets
-@example
-[iscsi "iqn.target.name"]
-  user = "CHAP username"
-  password = "CHAP password"
-  initiator-name = "iqn.qemu.test:my-initiator"
-  # header digest is one of CRC32C|CRC32C-NONE|NONE-CRC32C|NONE
-  header-digest = "CRC32C"
-@end example
-
-
-Howto use a configuration file to set iSCSI configuration options:
-@example
-cat >iscsi.conf <<EOF
-[iscsi]
-  user = "me"
-  password = "my password"
-  initiator-name = "iqn.qemu.test:my-initiator"
-  header-digest = "CRC32C"
-EOF
-
-qemu-system-i386 -drive file=iscsi://127.0.0.1/iqn.qemu.test/1 \
-    -readconfig iscsi.conf
-@end example
-
-
-Howto set up a simple iSCSI target on loopback and accessing it via QEMU:
-@example
-This example shows how to set up an iSCSI target with one CDROM and one DISK
-using the Linux STGT software target. This target is available on Red Hat based
-systems as the package 'scsi-target-utils'.
-
-tgtd --iscsi portal=127.0.0.1:3260
-tgtadm --lld iscsi --op new --mode target --tid 1 -T iqn.qemu.test
-tgtadm --lld iscsi --mode logicalunit --op new --tid 1 --lun 1 \
-    -b /IMAGES/disk.img --device-type=disk
-tgtadm --lld iscsi --mode logicalunit --op new --tid 1 --lun 2 \
-    -b /IMAGES/cd.iso --device-type=cd
-tgtadm --lld iscsi --op bind --mode target --tid 1 -I ALL
-
-qemu-system-i386 -iscsi initiator-name=iqn.qemu.test:my-initiator \
-    -boot d -drive file=iscsi://127.0.0.1/iqn.qemu.test/1 \
-    -cdrom iscsi://127.0.0.1/iqn.qemu.test/2
-@end example
-
-@node disk_images_gluster
-@subsection GlusterFS disk images
-
-GlusterFS is a user space distributed file system.
-
-You can boot from the GlusterFS disk image with the command:
-@example
-URI:
-qemu-system-x86_64 -drive file=gluster[+@var{type}]://[@var{host}[:@var{port}]]/@var{volume}/@var{path}
-                               [?socket=...][,file.debug=9][,file.logfile=...]
-
-JSON:
-qemu-system-x86_64 'json:@{"driver":"qcow2",
-                           "file":@{"driver":"gluster",
-                                    "volume":"testvol","path":"a.img","debug":9,"logfile":"...",
-                                    "server":[@{"type":"tcp","host":"...","port":"..."@},
-                                              @{"type":"unix","socket":"..."@}]@}@}'
-@end example
-
-@var{gluster} is the protocol.
-
-@var{type} specifies the transport type used to connect to gluster
-management daemon (glusterd). Valid transport types are
-tcp and unix. In the URI form, if a transport type isn't specified,
-then tcp type is assumed.
-
-@var{host} specifies the server where the volume file specification for
-the given volume resides. This can be either a hostname or an ipv4 address.
-If transport type is unix, then @var{host} field should not be specified.
-Instead @var{socket} field needs to be populated with the path to unix domain
-socket.
-
-@var{port} is the port number on which glusterd is listening. This is optional
-and if not specified, it defaults to port 24007. If the transport type is unix,
-then @var{port} should not be specified.
-
-@var{volume} is the name of the gluster volume which contains the disk image.
-
-@var{path} is the path to the actual disk image that resides on gluster volume.
-
-@var{debug} is the logging level of the gluster protocol driver. Debug levels
-are 0-9, with 9 being the most verbose, and 0 representing no debugging output.
-The default level is 4. The current logging levels defined in the gluster source
-are 0 - None, 1 - Emergency, 2 - Alert, 3 - Critical, 4 - Error, 5 - Warning,
-6 - Notice, 7 - Info, 8 - Debug, 9 - Trace
-
-@var{logfile} is a commandline option to mention log file path which helps in
-logging to the specified file and also help in persisting the gfapi logs. The
-default is stderr.
-
-
-
-
-You can create a GlusterFS disk image with the command:
-@example
-qemu-img create gluster://@var{host}/@var{volume}/@var{path} @var{size}
-@end example
-
-Examples
-@example
-qemu-system-x86_64 -drive file=gluster://1.2.3.4/testvol/a.img
-qemu-system-x86_64 -drive file=gluster+tcp://1.2.3.4/testvol/a.img
-qemu-system-x86_64 -drive file=gluster+tcp://1.2.3.4:24007/testvol/dir/a.img
-qemu-system-x86_64 -drive file=gluster+tcp://[1:2:3:4:5:6:7:8]/testvol/dir/a.img
-qemu-system-x86_64 -drive file=gluster+tcp://[1:2:3:4:5:6:7:8]:24007/testvol/dir/a.img
-qemu-system-x86_64 -drive file=gluster+tcp://server.domain.com:24007/testvol/dir/a.img
-qemu-system-x86_64 -drive file=gluster+unix:///testvol/dir/a.img?socket=/tmp/glusterd.socket
-qemu-system-x86_64 -drive file=gluster+rdma://1.2.3.4:24007/testvol/a.img
-qemu-system-x86_64 -drive file=gluster://1.2.3.4/testvol/a.img,file.debug=9,file.logfile=/var/log/qemu-gluster.log
-qemu-system-x86_64 'json:@{"driver":"qcow2",
-                           "file":@{"driver":"gluster",
-                                    "volume":"testvol","path":"a.img",
-                                    "debug":9,"logfile":"/var/log/qemu-gluster.log",
-                                    "server":[@{"type":"tcp","host":"1.2.3.4","port":24007@},
-                                              @{"type":"unix","socket":"/var/run/glusterd.socket"@}]@}@}'
-qemu-system-x86_64 -drive driver=qcow2,file.driver=gluster,file.volume=testvol,file.path=/path/a.img,
-                                       file.debug=9,file.logfile=/var/log/qemu-gluster.log,
-                                       file.server.0.type=tcp,file.server.0.host=1.2.3.4,file.server.0.port=24007,
-                                       file.server.1.type=unix,file.server.1.socket=/var/run/glusterd.socket
-@end example
-
-@node disk_images_ssh
-@subsection Secure Shell (ssh) disk images
-
-You can access disk images located on a remote ssh server
-by using the ssh protocol:
-
-@example
-qemu-system-x86_64 -drive file=ssh://[@var{user}@@]@var{server}[:@var{port}]/@var{path}[?host_key_check=@var{host_key_check}]
-@end example
-
-Alternative syntax using properties:
-
-@example
-qemu-system-x86_64 -drive file.driver=ssh[,file.user=@var{user}],file.host=@var{server}[,file.port=@var{port}],file.path=@var{path}[,file.host_key_check=@var{host_key_check}]
-@end example
-
-@var{ssh} is the protocol.
-
-@var{user} is the remote user.  If not specified, then the local
-username is tried.
-
-@var{server} specifies the remote ssh server.  Any ssh server can be
-used, but it must implement the sftp-server protocol.  Most Unix/Linux
-systems should work without requiring any extra configuration.
-
-@var{port} is the port number on which sshd is listening.  By default
-the standard ssh port (22) is used.
-
-@var{path} is the path to the disk image.
-
-The optional @var{host_key_check} parameter controls how the remote
-host's key is checked.  The default is @code{yes} which means to use
-the local @file{.ssh/known_hosts} file.  Setting this to @code{no}
-turns off known-hosts checking.  Or you can check that the host key
-matches a specific fingerprint:
-@code{host_key_check=md5:78:45:8e:14:57:4f:d5:45:83:0a:0e:f3:49:82:c9:c8}
-(@code{sha1:} can also be used as a prefix, but note that OpenSSH
-tools only use MD5 to print fingerprints).
-
-Currently authentication must be done using ssh-agent.  Other
-authentication methods may be supported in future.
-
-Note: Many ssh servers do not support an @code{fsync}-style operation.
-The ssh driver cannot guarantee that disk flush requests are
-obeyed, and this causes a risk of disk corruption if the remote
-server or network goes down during writes.  The driver will
-print a warning when @code{fsync} is not supported:
-
-warning: ssh server @code{ssh.example.com:22} does not support fsync
-
-With sufficiently new versions of libssh2 and OpenSSH, @code{fsync} is
-supported.
+@include docs/qemu-block-drivers.texi
 
 @node pcsys_network
 @section Network emulation