diff options
| author | Stefan Hajnoczi <stefanha@linux.vnet.ibm.com> | 2011-11-17 13:40:32 +0000 |
|---|---|---|
| committer | Kevin Wolf <kwolf@redhat.com> | 2011-12-05 14:51:38 +0100 |
| commit | fb0490f69feb96b7e92457f176dc834ff0b00b09 (patch) | |
| tree | 78f832101d9988753dac64f1f47946f2fa306a97 /qemu-options.hx | |
| parent | ab1859218a95977dc6881fcccce328d8146a6bdb (diff) | |
block: add -drive copy-on-read=on|off
This patch adds the -drive copy-on-read=on|off command-line option:
copy-on-read=on|off
copy-on-read is "on" or "off" and enables whether to copy read backing
file sectors into the image file. Copy-on-read avoids accessing the
same backing file sectors repeatedly and is useful when the backing
file is over a slow network. By default copy-on-read is off.
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Diffstat (limited to 'qemu-options.hx')
| -rw-r--r-- | qemu-options.hx | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/qemu-options.hx b/qemu-options.hx index 25a7be7948..b3db10c0ad 100644 --- a/qemu-options.hx +++ b/qemu-options.hx @@ -135,7 +135,7 @@ DEF("drive", HAS_ARG, QEMU_OPTION_drive, " [,cyls=c,heads=h,secs=s[,trans=t]][,snapshot=on|off]\n" " [,cache=writethrough|writeback|none|directsync|unsafe][,format=f]\n" " [,serial=s][,addr=A][,id=name][,aio=threads|native]\n" - " [,readonly=on|off]\n" + " [,readonly=on|off][,copy-on-read=on|off]\n" " [[,bps=b]|[[,bps_rd=r][,bps_wr=w]]][[,iops=i]|[[,iops_rd=r][,iops_wr=w]]\n" " use 'file' as a drive image\n", QEMU_ARCH_ALL) STEXI @@ -187,6 +187,9 @@ host disk is full; report the error to the guest otherwise). The default setting is @option{werror=enospc} and @option{rerror=report}. @item readonly Open drive @option{file} as read-only. Guest write attempts will fail. +@item copy-on-read=@var{copy-on-read} +@var{copy-on-read} is "on" or "off" and enables whether to copy read backing +file sectors into the image file. @end table By default, writethrough caching is used for all block device. This means that @@ -218,6 +221,10 @@ like your host losing power, the disk storage getting disconnected accidently, etc. you're image will most probably be rendered unusable. When using the @option{-snapshot} option, unsafe caching is always used. +Copy-on-read avoids accessing the same backing file sectors repeatedly and is +useful when the backing file is over a slow network. By default copy-on-read +is off. + Instead of @option{-cdrom} you can use: @example qemu -drive file=file,index=2,media=cdrom |