| qemu-options.hx (a67a47d2b559a7733c3f89aeb2d81b19d2c027e4) | qemu-options.hx (92196b2f5664d5defa778b1b24df56e2239b5e93) |
|---|---|
| 1HXCOMM Use DEFHEADING() to define headings in both help text and texi 2HXCOMM Text between STEXI and ETEXI are copied to texi version and 3HXCOMM discarded from C version 4HXCOMM DEF(option, HAS_ARG/0, opt_enum, opt_help, arch_mask) is used to 5HXCOMM construct option structures, enums and help message for specified 6HXCOMM architectures. 7HXCOMM HXCOMM can be used for comments, discarded from both texi and C 8 --- 119 unchanged lines hidden (view full) --- 128Use @var{file} as CD-ROM image (you cannot use @option{-hdc} and 129@option{-cdrom} at the same time). You can use the host CD-ROM by 130using @file{/dev/cdrom} as filename (@pxref{host_drives}). 131ETEXI 132 133DEF("drive", HAS_ARG, QEMU_OPTION_drive, 134 "-drive [file=file][,if=type][,bus=n][,unit=m][,media=d][,index=i]\n" 135 " [,cyls=c,heads=h,secs=s[,trans=t]][,snapshot=on|off]\n" | 1HXCOMM Use DEFHEADING() to define headings in both help text and texi 2HXCOMM Text between STEXI and ETEXI are copied to texi version and 3HXCOMM discarded from C version 4HXCOMM DEF(option, HAS_ARG/0, opt_enum, opt_help, arch_mask) is used to 5HXCOMM construct option structures, enums and help message for specified 6HXCOMM architectures. 7HXCOMM HXCOMM can be used for comments, discarded from both texi and C 8 --- 119 unchanged lines hidden (view full) --- 128Use @var{file} as CD-ROM image (you cannot use @option{-hdc} and 129@option{-cdrom} at the same time). You can use the host CD-ROM by 130using @file{/dev/cdrom} as filename (@pxref{host_drives}). 131ETEXI 132 133DEF("drive", HAS_ARG, QEMU_OPTION_drive, 134 "-drive [file=file][,if=type][,bus=n][,unit=m][,media=d][,index=i]\n" 135 " [,cyls=c,heads=h,secs=s[,trans=t]][,snapshot=on|off]\n" |
| 136 " [,cache=writethrough|writeback|none|unsafe][,format=f]\n" | 136 " [,cache=writethrough|writeback|none|directsync|unsafe][,format=f]\n" |
| 137 " [,serial=s][,addr=A][,id=name][,aio=threads|native]\n" 138 " [,readonly=on|off]\n" 139 " use 'file' as a drive image\n", QEMU_ARCH_ALL) 140STEXI 141@item -drive @var{option}[,@var{option}[,@var{option}[,...]]] 142@findex -drive 143 144Define a new drive. Valid options are: --- 14 unchanged lines hidden (view full) --- 159of available connectors of a given interface type. 160@item media=@var{media} 161This option defines the type of the media: disk or cdrom. 162@item cyls=@var{c},heads=@var{h},secs=@var{s}[,trans=@var{t}] 163These options have the same definition as they have in @option{-hdachs}. 164@item snapshot=@var{snapshot} 165@var{snapshot} is "on" or "off" and allows to enable snapshot for given drive (see @option{-snapshot}). 166@item cache=@var{cache} | 137 " [,serial=s][,addr=A][,id=name][,aio=threads|native]\n" 138 " [,readonly=on|off]\n" 139 " use 'file' as a drive image\n", QEMU_ARCH_ALL) 140STEXI 141@item -drive @var{option}[,@var{option}[,@var{option}[,...]]] 142@findex -drive 143 144Define a new drive. Valid options are: --- 14 unchanged lines hidden (view full) --- 159of available connectors of a given interface type. 160@item media=@var{media} 161This option defines the type of the media: disk or cdrom. 162@item cyls=@var{c},heads=@var{h},secs=@var{s}[,trans=@var{t}] 163These options have the same definition as they have in @option{-hdachs}. 164@item snapshot=@var{snapshot} 165@var{snapshot} is "on" or "off" and allows to enable snapshot for given drive (see @option{-snapshot}). 166@item cache=@var{cache} |
| 167@var{cache} is "none", "writeback", "unsafe", or "writethrough" and controls how the host cache is used to access block data. | 167@var{cache} is "none", "writeback", "unsafe", "directsync" or "writethrough" and controls how the host cache is used to access block data. |
| 168@item aio=@var{aio} 169@var{aio} is "threads", or "native" and selects between pthread based disk I/O and native Linux AIO. 170@item format=@var{format} 171Specify which disk @var{format} will be used rather than detecting 172the format. Can be used to specifiy format=raw to avoid interpreting 173an untrusted format header. 174@item serial=@var{serial} 175This option specifies the serial number to assign to the device. --- 18 unchanged lines hidden (view full) --- 194present in the host page cache. This is safe as long as you trust your host. 195If your host crashes or loses power, then the guest may experience data 196corruption. 197 198The host page cache can be avoided entirely with @option{cache=none}. This will 199attempt to do disk IO directly to the guests memory. QEMU may still perform 200an internal copy of the data. 201 | 168@item aio=@var{aio} 169@var{aio} is "threads", or "native" and selects between pthread based disk I/O and native Linux AIO. 170@item format=@var{format} 171Specify which disk @var{format} will be used rather than detecting 172the format. Can be used to specifiy format=raw to avoid interpreting 173an untrusted format header. 174@item serial=@var{serial} 175This option specifies the serial number to assign to the device. --- 18 unchanged lines hidden (view full) --- 194present in the host page cache. This is safe as long as you trust your host. 195If your host crashes or loses power, then the guest may experience data 196corruption. 197 198The host page cache can be avoided entirely with @option{cache=none}. This will 199attempt to do disk IO directly to the guests memory. QEMU may still perform 200an internal copy of the data. 201 |
| 202The host page cache can be avoided while only sending write notifications to 203the guest when the data has been reported as written by the storage subsystem 204using @option{cache=directsync}. 205 |
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| 202Some block drivers perform badly with @option{cache=writethrough}, most notably, 203qcow2. If performance is more important than correctness, 204@option{cache=writeback} should be used with qcow2. 205 206In case you don't care about data integrity over host failures, use 207cache=unsafe. This option tells qemu that it never needs to write any data 208to the disk but can instead keeps things in cache. If anything goes wrong, 209like your host losing power, the disk storage getting disconnected accidently, --- 2241 unchanged lines hidden --- | 206Some block drivers perform badly with @option{cache=writethrough}, most notably, 207qcow2. If performance is more important than correctness, 208@option{cache=writeback} should be used with qcow2. 209 210In case you don't care about data integrity over host failures, use 211cache=unsafe. This option tells qemu that it never needs to write any data 212to the disk but can instead keeps things in cache. If anything goes wrong, 213like your host losing power, the disk storage getting disconnected accidently, --- 2241 unchanged lines hidden --- |