aboutsummaryrefslogtreecommitdiff
path: root/docs/specs
AgeCommit message (Collapse)Author
2012-08-06docs: add lazy refcounts bit to qcow2 specificationStefan Hajnoczi
The lazy refcounts bit indicates that this image can take advantage of the dirty bit and that refcount updates can be postponed. Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-08-06docs: add dirty bit to qcow2 specificationStefan Hajnoczi
The dirty bit will make it possible to perform lazy refcount updates, where the image file is not kept consistent all the time. Upon opening a dirty image file, it is necessary to perform a consistency check and repair any incorrect refcounts. Therefore the dirty bit must be an incompatible feature bit. We don't want old programs accessing a file with stale refcounts. Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-06-24spapr: Add "memop" hypercallBenjamin Herrenschmidt
This adds a qemu-specific hypervisor call to the pseries machine which allows to do what amounts to memmove, memcpy and xor over regions of physical memory such as the framebuffer. This is the simplest way to get usable framebuffer speed from SLOF since the framebuffer isn't mapped in the VRMA and so would otherwise require an hcall per 8 bytes access. The performance is still not great but usable, and can be improved with a more complex implementation of the hcall itself if needed. This also adds some documentation for the qemu-specific hypercalls that we add to PAPR along with a new qemu,hypertas-functions property that mirrors ibm,hypertas-functions and provides some discoverability for the new calls. Note: I chose note to advertise H_RTAS to the guest via that mechanism. This is done on purpose, the guest uses the normal RTAS interfaces provided by qemu (including SLOF) which internally calls H_RTAS. We might in the future implement part (or even all) of RTAS inside the guest like IBM's firmware does and replace H_RTAS with some finer grained set of private hypercalls. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Alexander Graf <agraf@suse.de>
2012-05-02docs: fix one issue in qcow2 specsZhi Yong Wu
Signed-off-by: Zhi Yong Wu <wuzhy@linux.vnet.ibm.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-04-20Specification for qcow2 version 3Kevin Wolf
This updates the qcow2 specification to cover version 3. It contains the following changes: - Added compatible/incompatible/auto-clear feature bits plus an optional feature name table to allow useful error messages even if an older version doesn't know some feature at all. - Configurable refcount width. If you don't want to use internal snapshots, make refcounts one bit and save cache space and I/O. - Zero cluster flags. This allows discard even with a backing file that doesn't contain zeros. It is also useful for copy-on-read/image streaming, as you'll want to keep sparseness without accessing the remote image for an unallocated cluster all the time. - Fixed internal snapshot metadata to use 64 bit VM state size. You can't save a snapshot of a VM with >= 4 GB RAM today. - Extended internal snapshot metadata to contain the disk size, so that resizing images that have snapshots can be allowed in the future. Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-04-15acpi_piix4: Re-define PCI hotplug eject register readAlex Williamson
The PCI hotplug eject register has always returned 0, so let's redefine it as a hotplug feature register. The existing model of using separate up & down read-only registers and an eject via write to this register becomes the base implementation. As we make use of new interfaces we'll set bits here to allow the BIOS and AML implementation to optimize for the platform implementation. Signed-off-by: Alex Williamson <alex.williamson@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2012-04-15acpi_piix4: Remove PCI_RMV_BASE write codeAlex Williamson
Clarify this register as read-only and remove write code. No change in existing behavior. Signed-off-by: Alex Williamson <alex.williamson@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2012-04-15acpi_piix4: Disallow write to up/down PCI hotplug registersAlex Williamson
The write side of these registers is never used and actually can't be used as defined because any read/modify/write sequence from the guest potentially races with qemu. Drop the write support and define these as read-only registers. Signed-off-by: Alex Williamson <alex.williamson@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2012-04-07Replace Qemu by QEMU in internal documentationStefan Weil
The official spelling is QEMU. Signed-off-by: Stefan Weil <sw@weilnetz.de> Reviewed-by: Andreas Färber <afaerber@suse.de> Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
2011-12-15qcow2: Allow >4 GB VM stateKevin Wolf
This is a compatible extension to the snapshot header format that allows saving a 64 bit VM state size. Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2011-10-28qcow2: fix some errors and typo in qcow2.txtZhi Yong Wu
Signed-off-by: Zhi Yong Wu <wuzhy@linux.vnet.ibm.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2011-04-13docs: Describe zero data clusters in QED specificationStefan Hajnoczi
Zero data clusters are a space-efficient way of storing zeroed regions of the image. Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2011-03-16Add qcow2 documentationKevin Wolf
This adds a description of the qcow2 file format to the docs/ directory. Besides documenting what's there, which is never wrong, the document should provide a good basis for the discussion of format extensions (called "qcow3" in previous discussions) Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
2011-01-17document QEMU<->ACPIBIOS PCI hotplug interfaceMarcelo Tosatti
Document how QEMU communicates with ACPI BIOS for PCI hotplug. Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2010-12-17docs: Fix missing carets in QED specificationStefan Hajnoczi
For some reason the carets ('^') in the QED specification disappeared. This patch puts them back. Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2010-12-17docs: Add QED image format specificationStefan Hajnoczi
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2010-08-10Device specification for shared memory PCI deviceCam Macdonell
Signed-off-by: Cam Macdonell <cam@cs.ualberta.ca> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>