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Merge remote-tracking branch 'kwolf/for-anthony' into staging

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* kwolf/for-anthony:
  coroutine-sigaltstack.c: Use stack_t, not struct sigaltstack
  stream: fix ratelimit_set_speed
  atapi: make change media detection for guests easier
  Documentation: Update image format information
  Documentation: Update block cache mode information

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
This commit is contained in:
Anthony Liguori 2012-11-30 10:24:24 -06:00
commit 90e07938aa
7 changed files with 228 additions and 92 deletions
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4
coroutine-sigaltstack.c
View File

@ -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;

13
hw/ide/atapi.c
View File

@ -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->sense_key = UNIT_ATTENTION;
s->asc = ASC_MEDIUM_MAY_HAVE_CHANGED;
}
return;
}

6
hw/ide/core.c
View File

@ -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)));
}

2
include/qemu/ratelimit.h
View File

@ -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

167
qemu-doc.texi
View File

@ -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

88
qemu-img.texi
View File

@ -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.
@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
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.
@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 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.
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

38
qemu-options.hx
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@ -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.
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.
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.
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