diff options
-rw-r--r-- | coroutine-sigaltstack.c | 4 | ||||
-rw-r--r-- | hw/ide/atapi.c | 15 | ||||
-rw-r--r-- | hw/ide/core.c | 6 | ||||
-rw-r--r-- | include/qemu/ratelimit.h | 2 | ||||
-rw-r--r-- | qemu-doc.texi | 167 | ||||
-rw-r--r-- | qemu-img.texi | 84 | ||||
-rw-r--r-- | qemu-options.hx | 40 |
7 files changed, 227 insertions, 91 deletions
diff --git a/coroutine-sigaltstack.c b/coroutine-sigaltstack.c index 861e878..39dbaa5 100644 --- a/coroutine-sigaltstack.c +++ b/coroutine-sigaltstack.c @@ -171,8 +171,8 @@ static Coroutine *coroutine_new(void) CoroutineThreadState *coTS; struct sigaction sa; struct sigaction osa; - struct sigaltstack ss; - struct sigaltstack oss; + stack_t ss; + stack_t oss; sigset_t sigs; sigset_t osigs; jmp_buf old_env; diff --git a/hw/ide/atapi.c b/hw/ide/atapi.c index 685cbaa..861fd2b 100644 --- a/hw/ide/atapi.c +++ b/hw/ide/atapi.c @@ -1124,12 +1124,17 @@ void ide_atapi_cmd(IDEState *s) * GET_EVENT_STATUS_NOTIFICATION to detect such tray open/close * states rely on this behavior. */ - if (!s->tray_open && bdrv_is_inserted(s->bs) && s->cdrom_changed) { - ide_atapi_cmd_error(s, NOT_READY, ASC_MEDIUM_NOT_PRESENT); + if (!(atapi_cmd_table[s->io_buffer[0]].flags & ALLOW_UA) && + !s->tray_open && bdrv_is_inserted(s->bs) && s->cdrom_changed) { + + if (s->cdrom_changed == 1) { + ide_atapi_cmd_error(s, NOT_READY, ASC_MEDIUM_NOT_PRESENT); + s->cdrom_changed = 2; + } else { + ide_atapi_cmd_error(s, UNIT_ATTENTION, ASC_MEDIUM_MAY_HAVE_CHANGED); + s->cdrom_changed = 0; + } - s->cdrom_changed = 0; - s->sense_key = UNIT_ATTENTION; - s->asc = ASC_MEDIUM_MAY_HAVE_CHANGED; return; } diff --git a/hw/ide/core.c b/hw/ide/core.c index 8da894f..c4f93d0 100644 --- a/hw/ide/core.c +++ b/hw/ide/core.c @@ -2160,12 +2160,6 @@ static int ide_drive_post_load(void *opaque, int version_id) { IDEState *s = opaque; - if (version_id < 3) { - if (s->sense_key == UNIT_ATTENTION && - s->asc == ASC_MEDIUM_MAY_HAVE_CHANGED) { - s->cdrom_changed = 1; - } - } if (s->identify_set) { bdrv_set_enable_write_cache(s->bs, !!(s->identify_data[85] & (1 << 5))); } diff --git a/include/qemu/ratelimit.h b/include/qemu/ratelimit.h index c6ac281..d1610f1 100644 --- a/include/qemu/ratelimit.h +++ b/include/qemu/ratelimit.h @@ -42,7 +42,7 @@ static inline void ratelimit_set_speed(RateLimit *limit, uint64_t speed, uint64_t slice_ns) { limit->slice_ns = slice_ns; - limit->slice_quota = ((double)speed * 1000000000ULL) / slice_ns; + limit->slice_quota = ((double)speed * slice_ns)/1000000000ULL; } #endif diff --git a/qemu-doc.texi b/qemu-doc.texi index 6ff309d..6d7f50d 100644 --- a/qemu-doc.texi +++ b/qemu-doc.texi @@ -416,6 +416,7 @@ snapshots. * vm_snapshots:: VM snapshots * qemu_img_invocation:: qemu-img Invocation * qemu_nbd_invocation:: qemu-nbd Invocation +* disk_images_formats:: Disk image file formats * host_drives:: Using host drives * disk_images_fat_images:: Virtual FAT disk images * disk_images_nbd:: NBD access @@ -507,6 +508,172 @@ 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. + +@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), optional AES encryption, 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 (this is the default). +@code{compat=1.1} enables image format extensions that only QEMU 1.1 and +newer understand. 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 +If this option is set to @code{on}, the image is encrypted. + +Encryption uses the AES format which is very secure (128 bit keys). Use +a long password (16 characters) to get maximum protection. + +@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: off, metadata). An image with preallocated +metadata is initially larger but can improve performance when the image needs +to grow. + +@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. + +@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 +If this option is set to @code{on}, the image is encrypted. +@end table + +@item cow +User Mode Linux Copy On Write image format. It is supported only for +compatibility with previous versions. +Supported options: +@table @code +@item backing_file +File name of a base image (see @option{create} subcommand) +@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 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 +@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 diff --git a/qemu-img.texi b/qemu-img.texi index 60b83fc..00fca8d 100644 --- a/qemu-img.texi +++ b/qemu-img.texi @@ -226,7 +226,10 @@ After using this command to grow a disk image, you must use file system and partitioning tools inside the VM to actually begin using the new space on the device. @end table +@c man end +@ignore +@c man begin NOTES Supported image file formats: @table @option @@ -247,6 +250,13 @@ 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 (this is the default). +@code{compat=1.1} enables image format extensions that only QEMU 1.1 and +newer understand. 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 @@ -267,73 +277,33 @@ Preallocation mode (allowed values: off, metadata). An image with preallocated metadata is initially larger but can improve performance when the image needs to grow. -@end table +@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. -@item qed -Image format with support for backing files and compact image files (when your -filesystem or transport medium does not support holes). Good performance due -to less metadata than the more featureful qcow2 format, especially with -cache=writethrough or cache=directsync. Consider using qcow2 which will soon -have a similar optimization and is most actively developed. +This option can only be enabled if @code{compat=1.1} is specified. -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. Left for compatibility. +@item Other +QEMU also supports various other image file formats for compatibility with +older QEMU versions or other hypervisors, including VMDK, VDI, VHD (vpc), qcow1 +and QED. For a full list of supported formats see @code{qemu-img --help}. +For a more detailed description of these formats, see the QEMU Emulation User +Documentation. -Supported options: -@table @code -@item backing_file -File name of a base image (see @option{create} subcommand) -@item encryption -If this option is set to @code{on}, the image is encrypted. -@end table - -@item cow -User Mode Linux Copy On Write image format. Used to be the only growable -image format in QEMU. It is supported only for compatibility with -previous versions. It does not work on win32. -@item vdi -VirtualBox 1.1 compatible image format. -@item vmdk -VMware 3 and 4 compatible image format. - -Supported options: -@table @code -@item backing_fmt -Image format of the base image -@item compat6 -Create a VMDK version 6 image (instead of version 4) -@end table - -@item vpc -VirtualPC compatible image format (VHD). - -@item cloop -Linux Compressed Loop image, useful only to reuse directly compressed -CD-ROM images present for example in the Knoppix CD-ROMs. +The main purpose of the block drivers for these formats is image conversion. +For running VMs, it is recommended to convert the disk images to either raw or +qcow2 in order to achieve good performance. @end table @c man end -@ignore - @setfilename qemu-img @settitle QEMU disk image utility diff --git a/qemu-options.hx b/qemu-options.hx index fbcf079..de43b1b 100644 --- a/qemu-options.hx +++ b/qemu-options.hx @@ -206,33 +206,33 @@ Open drive @option{file} as read-only. Guest write attempts will fail. file sectors into the image file. @end table -By default, writethrough caching is used for all block device. This means that -the host page cache will be used to read and write data but write notification -will be sent to the guest only when the data has been reported as written by -the storage subsystem. - -Writeback caching will report data writes as completed as soon as the data is -present in the host page cache. This is safe as long as you trust your host. -If your host crashes or loses power, then the guest may experience data -corruption. +By default, the @option{cache=writeback} mode is used. It will report data +writes as completed as soon as the data is present in the host page cache. +This is safe as long as your guest OS makes sure to correctly flush disk caches +where needed. If your guest OS does not handle volatile disk write caches +correctly and your host crashes or loses power, then the guest may experience +data corruption. + +For such guests, you should consider using @option{cache=writethrough}. This +means that the host page cache will be used to read and write data, but write +notification will be sent to the guest only after QEMU has made sure to flush +each write to the disk. Be aware that this has a major impact on performance. The host page cache can be avoided entirely with @option{cache=none}. This will -attempt to do disk IO directly to the guests memory. QEMU may still perform -an internal copy of the data. +attempt to do disk IO directly to the guest's memory. QEMU may still perform +an internal copy of the data. Note that this is considered a writeback mode and +the guest OS must handle the disk write cache correctly in order to avoid data +corruption on host crashes. The host page cache can be avoided while only sending write notifications to -the guest when the data has been reported as written by the storage subsystem -using @option{cache=directsync}. - -Some block drivers perform badly with @option{cache=writethrough}, most notably, -qcow2. If performance is more important than correctness, -@option{cache=writeback} should be used with qcow2. +the guest when the data has been flushed to the disk using +@option{cache=directsync}. In case you don't care about data integrity over host failures, use -cache=unsafe. This option tells QEMU that it never needs to write any data -to the disk but can instead keeps things in cache. If anything goes wrong, +@option{cache=unsafe}. This option tells QEMU that it never needs to write any +data to the disk but can instead keep things in cache. If anything goes wrong, like your host losing power, the disk storage getting disconnected accidentally, -etc. you're image will most probably be rendered unusable. When using +etc. your 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 |