Commit Graph

21314 Commits

Author SHA1 Message Date
Guan Xuetao
4f23a1e645 unicore32-softmmu: Add unicore32-softmmu build support
This patch adds unicore32-softmmu build support, include configure,
makefile, arch_init, and all missing functions needed by softmmu.
Although all missing functions are empty, unicore32-softmmu could
be build successfully.
By 20120804: change QEMU_ARCH_UNICORE32 to 0x4000

Signed-off-by: Guan Xuetao <gxt@mprc.pku.edu.cn>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
2012-08-11 09:36:55 +00:00
Peter Maydell
b90372ad2a target-arm: Fix typos in comments
Fix a variety of typos in comments in target-arm files.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Peter Crosthwaite <peter.crosthwaite@petalogix.com>
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
2012-08-10 14:37:28 +01:00
Peter A. G. Crosthwaite
656267413c arm: translate: comment typo - s/middel/middle/
Signed-off-by: Peter A. G. Crosthwaite <peter.crosthwaite@petalogix.com>
Reviewed-by: Andreas Färber <afaerber@suse.de>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
2012-08-10 14:33:16 +01:00
Dunrong Huang
fb7c269ed6 vl.c: Exit QEMU early if no machine is found
We check whether the variable machine is NULL or not before accessing
it. If machine is NULL, exit QEMU with an error, this can avoids a
segfault error.

Markus Armbruster <armbru@redhat.com> adds that the segfault can be
reproduced as follows:

  $ qemu-system-xtensa -cpu help

Signed-off-by: Dunrong Huang <riegamaths@gmail.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
2012-08-10 14:28:11 +01:00
Stefan Hajnoczi
166f3c7b70 qemu-iotests: skip 039 with ./check -nocache
When the qemu-io --nocache option is used the 039 test case cannot abort
QEMU at a point where the image is dirty.  Skip the test case.

Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-08-10 10:25:12 +02:00
Stefan Hajnoczi
058f8f16db block: add BLOCK_O_CHECK for qemu-img check
Image formats with a dirty bit, like qed and qcow2, repair dirty image
files upon open with BDRV_O_RDWR.  Performing automatic repair when
qemu-img check runs is not ideal because the bdrv_open() call repairs
the image before the actual bdrv_check() call from qemu-img.c.

Fix this "double repair" since it leads to confusing output from
qemu-img check.  Tell the block driver that this image is being opened
just for bdrv_check().  This skips automatic repair and qemu-img.c can
invoke it manually with bdrv_check().

Update the golden output for qemu-iotests 039 to reflect the new
qemu-img check output.

Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-08-10 10:25:12 +02:00
Stefan Hajnoczi
acbe59829e qcow2: mark image clean after repair succeeds
The dirty bit is cleared after image repair succeeds in qcow2_open().
Move this into qcow2_check() so that all callers benefit from this
behavior when fix mode is enabled.

This is necessary so qemu-img check can call .bdrv_check() and mark the
image clean.

Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-08-10 10:25:12 +02:00
Stefan Hajnoczi
b10170aca0 qed: mark image clean after repair succeeds
The dirty bit is cleared after image repair succeeds in qed_open().
Move this into qed_check() so that all callers benefit from this
behavior when fix=true.

This is necessary so qemu-img check can call .bdrv_check() and mark the
image clean.

Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-08-10 10:25:12 +02:00
Paolo Bonzini
1f212b9d3e blockdev: flip default cache mode from writethrough to writeback
Now all major device models (IDE, SCSI, virtio) can choose between
writethrough and writeback at run-time, and virtio will even revert
to writethrough if the guest is not capable of sending flushes.  So
we can change the default to writeback at last.

Tested, for lack of a better idea, with a breakpoint on bdrv_open
and all cache choices one by one.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-08-10 10:25:12 +02:00
Paolo Bonzini
9315cbfd8d virtio-blk: disable write cache if not negotiated
If the guest does not support flushes, we should run in writethrough mode.
The setting is temporary until the next reset, so that for example the
BIOS will run in writethrough mode while Linux will run with a writeback
cache.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-08-10 10:25:12 +02:00
Paolo Bonzini
13e3dce068 virtio-blk: support VIRTIO_BLK_F_CONFIG_WCE
Also rename VIRTIO_BLK_F_WCACHE to VIRTIO_BLK_F_WCE for consistency with
the spec.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-08-10 10:25:12 +02:00
Kevin Wolf
353a41be05 qemu-iotests: Save some sed processes
Instead of building a huge pipeline, just pass all expressions to a
single sed process.

Suggested-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
2012-08-10 10:25:12 +02:00
Jason Baron
ea8d82a1ed ahci: Fix sglist memleak in ahci_dma_rw_buf()
I noticed that in hw/ide/ahci:ahci_dma_rw_buf() we do not free the sglist. Thus,
I've added a call to qemu_sglist_destroy() to fix this memory leak.

In addition, I've adeed a call in qemu_sglist_destroy() to 0 all of the sglist
fields, in case there is some other codepath that tries to free the sglist.

Signed-off-by: Jason Baron <jbaron@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-08-10 10:25:12 +02:00
Jason Baron
61f52e06f0 ahci: Fix ahci cdrom read corruptions for reads > 128k
While testing q35, which has its cdrom attached to the ahci controller, I found
that the Fedora 17 install would panic on boot. The panic occurs while
squashfs is trying to read from the cdrom. The errors are:

[    8.622711] SQUASHFS error: xz_dec_run error, data probably corrupt
[    8.625180] SQUASHFS error: squashfs_read_data failed to read block
0x20be48a

I was also able to produce corrupt data reads using an installed piix based
qemu machine, using 'dd'. I found that the corruptions were only occuring when
then read size was greater than 128k. For example, the following command
results in corrupted reads:

dd if=/dev/sr0 of=/tmp/blah bs=256k iflag=direct

The > 128k size reads exercise a different code path than 128k and below. In
ide_atapi_cmd_read_dma_cb() s->io_buffer_size is capped at 128k. Thus,
ide_atapi_cmd_read_dma_cb() is called a second time when the read is > 128k.
However, ahci_dma_rw_buf() restart the read from offset 0, instead of at 128k.
Thus, resulting in a corrupted read.

To fix this, I've introduced 'io_buffer_offset' field in IDEState to keep
track of the offset. I've also modified ahci_populate_sglist() to take a new
3rd offset argument, so that the sglist is property initialized.

I've tested this patch using 'dd' testing, and Fedora 17 now correctly boots
and installs on q35 with the cdrom ahci controller.

Signed-off-by: Jason Baron <jbaron@redhat.com>
Tested-by: Andreas Färber <afaerber@suse.de>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-08-10 10:25:12 +02:00
Avi Kivity
730a9c53b4 virtio-blk: fix use-after-free while handling scsi commands
The scsi passthrough handler falls through after completing a
request into the failure path, resulting in a use after free.

Reproducible by running a guest with aio=native on a block device.

Reported-by: Stefan Priebe <s.priebe@profihost.ag>
Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-08-10 10:25:11 +02:00
Bruce Rogers
3d1d965297 handle device help before accelerator set up
A command line device probe using just -device "?" gets processed
after qemu-kvm initializes the accelerator. If /dev/kvm is not
present, the accelerator check will fail (kvm is defaulted to on),
which causes libvirt to not be set up to handle qemu guests.

Moving the device help handling before the accelerator set up allows
the device probe to work in this configuration and libvirt succeeds
in setting up for a qemu hypervisor mode.

Signed-off-by: Bruce Rogers <brogers@suse.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
2012-08-09 19:53:01 +00:00
Blue Swirl
d3da41e32b Merge branch 'x86cpu_qom_tcg_v2' of git://github.com/imammedo/qemu
* 'x86cpu_qom_tcg_v2' of git://github.com/imammedo/qemu:
  target-i386: move tcg initialization into x86_cpu_initfn()
  cleanup cpu_set_debug_excp_handler
  target-xtensa: drop usage of prev_debug_excp_handler
  target-i386: drop usage of prev_debug_excp_handler
2012-08-09 18:44:49 +00:00
Stefano Stabellini
8227421e04 qemu_rearm_alarm_timer: do not call rearm if the next deadline is INT64_MAX
qemu_rearm_alarm_timer partially duplicates the code in
qemu_next_alarm_deadline to figure out if it needs to rearm the timer.
If it calls qemu_next_alarm_deadline, it always rearms the timer even if
the next deadline is INT64_MAX.

This patch simplifies the behavior of qemu_rearm_alarm_timer and removes
the duplicated code, always calling qemu_next_alarm_deadline and only
rearming the timer if the deadline is less than INT64_MAX.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Reviewed-by: Stefan Weil <sw@weilnetz.de>
Tested-by: Andreas Färber <andreas.faerber@web.de>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
2012-08-09 18:42:38 +00:00
Max Filippov
82e5d46414 target-xtensa: make 'sim' to be the default machine
This fixes the following error:

    $ qemu-system-xtensa -cpu help
    Segmentation fault

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
2012-08-09 18:38:23 +00:00
Max Filippov
e38077ff90 target-xtensa: make default CPU depend on target endianness
This makes usable default for -cpu option both for qemu-system-xtensa
and qemu-system-xtensaeb fixing the following error:

    $ qemu-system-xtensaeb -M sim
    Unable to find CPU definition

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Tested-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
2012-08-09 18:37:30 +00:00
Nathan Froyd
f1cb0951c5 MIPS: Correct FCR0 initialization
This change addresses a problem where QEMU incorrectly traps on
floating-point MADD group instructions with SIGILL, at least while
emulating MIPS32r2 processors.  These instructions use the COP1X major
opcode and include ones like:

	madd.d	$f2,$f4,$f2,$f6

 Here's Nathan's original analysis of the problem:

"QEMU essentially does:

  d = find_cpu (cpu_string)	// get CPU definition
  fpu_init (env, d)		// initialize fpu state (init FCR0, basically)
  cpu_reset (env)

...and the cpu_reset call clears all interesting state that fpu_init
setup, then proceeds to reinitialize all the CP0 registers...but not
FCR0."

 I have verified this change with system emulation running the GDB test
suite for the mips-sde-elf target (o32, big endian, 24Kf CPU emulated),
there were 55 progressions and no regressions.

Signed-off-by: Maciej W. Rozycki <macro@codesourcery.com>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
2012-08-09 18:36:19 +00:00
Blue Swirl
832a226b62 scsi-bus: remove overlapping entry
LOAD_UNLOAD and START_STOP have same value, so the table
entry is initialized twice. Spotted by Clang compiler.

Remove LOAD_UNLOAD entry since START_STOP entry already
represents both.

Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
2012-08-09 18:34:57 +00:00
Blue Swirl
a1e64eb96c xilinx_axienet: avoid useless self-assignment
Statement s=s; makes little sense, remove it. Spotted by Clang
compiler.

Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
2012-08-09 18:34:57 +00:00
Blue Swirl
1846ec2c6a user: fix accidental AREG0 use
Global register AREG0 was always assumed to be usable in user-exec.c,
but this is incorrect for several targets.

Fix with #ifdeffery and by using other variables.

Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
2012-08-09 18:34:57 +00:00
Blue Swirl
427a1a2cb1 qapi: avoid reserved keywords
Clang compiler complained about use of reserved word 'restrict' in SLIRP
and QAPI.

Prefix C keywords with "q_", adjust SLIRP accordingly.

Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
2012-08-09 18:34:57 +00:00
Blue Swirl
8954bae3ce sparc: fix expression with uninitialized initial value
err was uninitialized, it's not OK to use |=. Spotted by Clang
compiler.

Fix by implementing the earlier statement which initializes the variable.

Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
2012-08-09 18:34:57 +00:00
Blue Swirl
acfbe712df sparc: fix floppy TC line setup
The qemu_irq for Terminal Count (TC) line between FDC and Slavio misc
device was created only after use, spotted by Clang compiler. Also,
it was not created if the FDC didn't exist.

Rearrange code to fix order. Always create the TC line.

Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
2012-08-09 18:34:57 +00:00
Hervé Poussineau
cea936b1b5 esp: add Tekram DC-390 emulation (PC SCSI adapter)
Difference with AMD PCscsi is that DC-390 contains a EEPROM,
and that a romfile is available to add INT13 support.

This has been successfully tested on:
- MS DOS 6.22 (using DC390 ASPI driver)
- MS Windows 98 SE (using DC390 driver)
- MS Windows NT 3.1 (using DC390 driver)
- MS Windows NT 4.0 (using DC390 driver)
- hard disk and cdrom boot

Signed-off-by: Hervé Poussineau <hpoussin@reactos.org>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
2012-08-09 18:21:49 +00:00
Hervé Poussineau
bde299a247 Revert "pci: add some stubs"
This reverts commit 0883c5159f.

Those stubs were only used by PCI ESP emulation, which is now
not compiled on architectures which have no PCI bus support.

Signed-off-by: Hervé Poussineau <hpoussin@reactos.org>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
2012-08-09 18:21:47 +00:00
Hervé Poussineau
aebcf56fde esp: move PCI emulation to a new file esp-pci.c
sparc machines loose ability to instanciate PCI ESP SCSI adapter,
which is not a big loose as they don't have PCI bus support.

Signed-off-by: Hervé Poussineau <hpoussin@reactos.org>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
2012-08-09 18:21:47 +00:00
Hervé Poussineau
9c7e23fc4d esp: move some definitions to header file
These will be used by next commits.

Signed-off-by: Hervé Poussineau <hpoussin@reactos.org>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
2012-08-09 18:21:46 +00:00
Paolo Bonzini
5222aaf223 scsi-disk: add support for the UNMAP command
The unmap command can reuse the same infrastructure as MODE SELECT
for reading the descriptor list into memory.  The descriptors are
processed sequentially.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2012-08-09 15:35:45 +02:00
Paolo Bonzini
a084a703df scsi-disk: improve out-of-range LBA detection for WRITE SAME
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2012-08-09 15:35:45 +02:00
Paolo Bonzini
46e3f30e3c scsi-disk: more assertions and resets for aiocb
Leaving the aiocb to a non-NULL value leads to an assertion failure when
rerror/werror are set to stop or enospc, and the operation is retried.
scsi-disk checks that the aiocb member is NULL before filling it.

This patch correctly resets the aiocb to NULL values everywhere,
and adds the dual assertion that the aiocb was non-NULL before
calling bdrv_acct_done.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2012-08-09 15:35:45 +02:00
Paolo Bonzini
4dd7c82cdb virtio-scsi: do not compare 32-bit QEMU tags against 64-bit virtio-scsi tags
This patch fixes a problem in handling task management functions
in virtio-scsi.  The cause of the problem is a mismatch between
the size of the tag in QEMU (32-bit) and virtio-scsi (64-bit).
Changing the QEMU size is hard because the migration format
uses 32 bits to store the tag; so just don't use the QEMU tag
(virtio-scsi only uses the tag for task management functions
anyway) and look up the full 64-bit tag in the hba_private field.

The reproducer is a bit obscure.  If you cause an I/O timeout
(for example with rerror=stop and doing 'cont' on the monitor
continuously without fixing the error), sooner or later the
guest will try to abort the command and reissue it.  At this
point, QEMU will report _two_ errors instead of one when you
hit 'c', because the first error has not been canceled correctly.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2012-08-09 15:04:09 +02:00
Ronnie Sahlberg
31459f463a iscsi: Pick default initiator-name based on the name of the VM
This patch updates the iscsi layer to automatically pick a 'unique'
initiator-name based on the name of the vm in case the user has not set
an explicit iqn-name to use.

Create a new function qemu_get_vm_name() that returns the name of the VM,
if specified.

This way we can thus create default names to use as the initiator name
based on the guest session.

If the VM is not named via the '-name' command line argument, the iscsi
initiator-name used wiull simply be

    iqn.2008-11.org.linux-kvm

If a name for the VM was specified with the '-name' option, iscsi will
use a default initiatorname of

    iqn.2008-11.org.linux-kvm:<name>

These names are just the default iscsi initiator name that qemu will
generate/use only when the user has not set an explicit initiator name
via the commandlines or config files.

Signed-off-by: Ronnie Sahlberg <ronniesahlberg@gmail.com>
2012-08-09 15:04:09 +02:00
Paolo Bonzini
f2ef4a6dd9 iscsi: reorganize code for parse_initiator_name
Merge the occurrences of the "iqn.2008-11.org.linux-kvm" string
to avoid duplication.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2012-08-08 14:51:59 +02:00
Paolo Bonzini
b93c94f7ec iscsi: do not leak initiator_name
The argument of iscsi_create_context is never freed by libiscsi,
which in fact calls strdup on it.  Avoid a leak.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2012-08-08 14:51:59 +02:00
Anthony Liguori
c03b0aa0ca Merge remote-tracking branch 'kraxel/usb.58' into staging
* kraxel/usb.58:
  usb-storage: fix SYNCHRONIZE_CACHE
  usb-storage: improve debug logging
2012-08-07 09:46:40 -05:00
Anthony Liguori
b262fce11a Merge remote-tracking branch 'kwolf/for-anthony' into staging
* kwolf/for-anthony:
  qemu-img: use QemuOpts instead of QEMUOptionParameter in resize function
  qemu-iotests: Be more flexible with image creation options
  qemu-iotests: add 039 qcow2 lazy refcounts test
  qemu-io: add "abort" command to simulate program crash
  qcow2: implement lazy refcounts
  qemu-iotests: ignore qemu-img create lazy_refcounts output
  docs: add lazy refcounts bit to qcow2 specification
  qcow2: introduce dirty bit
  docs: add dirty bit to qcow2 specification
  qemu-iotests: add qed.py image manipulation utility
  qapi: generalize documentation of streaming commands
  ide scsi: Mess with geometry only for hard disk devices
2012-08-07 09:46:24 -05:00
Gerd Hoffmann
54414218d7 usb-storage: fix SYNCHRONIZE_CACHE
Commit 5931065907 is incomplete,
we'll arrive in the scsi command complete callback in CSW state
and must handle that case correctly.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
2012-08-07 10:49:06 +02:00
Gerd Hoffmann
06f9847dc3 usb-storage: improve debug logging
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
2012-08-07 10:49:06 +02:00
Anthony Liguori
0b8db8fe15 slirp: fix build on mingw32
in_addr_t isn't available on mingw32.  Just use an unsigned long instead.  I
considered typedef'ing in_addr_t on mingw32 but this would potentially be
brittle if mingw32 did introduce the type.

Cc: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2012-08-06 19:31:55 -05:00
Dong Xu Wang
20caf0f766 qemu-img: use QemuOpts instead of QEMUOptionParameter in resize function
Signed-off-by: Dong Xu Wang <wdongxu@linux.vnet.ibm.com>
Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-08-06 22:39:14 +02:00
Kevin Wolf
b0869a46b2 qemu-iotests: Be more flexible with image creation options
qemu-iotests already filters out image creation options that may be
present or not in order to get the same output in both cases. However,
often it only considers the default value of the option. Cover all valid
values instead so that ./check -o name=value can be used successfull for
all of them.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-08-06 22:39:14 +02:00
Stefan Hajnoczi
dc68afe0f3 qemu-iotests: add 039 qcow2 lazy refcounts test
This tests establishes the basic post-conditions of the qcow2 lazy
refcounts features:

  1. If the image was closed normally, it is marked clean.

  2. If an allocating write was performed and the image was not closed
     normally, then it is marked dirty.

     a. Written data can be read back successfully.
     b. The image file can be repaired and will be marked clean again.
     c. The image file is automatically repaired when opened read/write.

Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-08-06 22:39:14 +02:00
Stefan Hajnoczi
e01c30d3e2 qemu-io: add "abort" command to simulate program crash
Avoiding data loss and corruption is the top requirement for image file
formats.  The qemu-io "abort" command makes it possible to simulate
program crashes and does not give the image format a chance to cleanly
shut down.  This command is useful for data integrity test cases.

Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-08-06 22:39:14 +02:00
Stefan Hajnoczi
bfe8043e92 qcow2: implement lazy refcounts
Lazy refcounts is a performance optimization for qcow2 that postpones
refcount metadata updates and instead marks the image dirty.  In the
case of crash or power failure the image will be left in a dirty state
and repaired next time it is opened.

Reducing metadata I/O is important for cache=writethrough and
cache=directsync because these modes guarantee that data is on disk
after each write (hence we cannot take advantage of caching updates in
RAM).  Refcount metadata is not needed for guest->file block address
translation and therefore does not need to be on-disk at the time of
write completion - this is the motivation behind the lazy refcount
optimization.

The lazy refcount optimization must be enabled at image creation time:

  qemu-img create -f qcow2 -o compat=1.1,lazy_refcounts=on a.qcow2 10G
  qemu-system-x86_64 -drive if=virtio,file=a.qcow2,cache=writethrough

Update qemu-iotests 031 and 036 since the extension header size changes
when we add feature bit table entries.

Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-08-06 22:39:14 +02:00
Stefan Hajnoczi
91cf8a35e7 qemu-iotests: ignore qemu-img create lazy_refcounts output
Hide the default lazy_refcounts=off output from qemu-img like we do with
other image creation options.  This ensures that existing golden outputs
continue to pass despite the new option that has been added.

Note that this patch applies before the one that actually introduces the
lazy_refcounts=on|off option.  This ensures git-bisect(1) continues to
work.

Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-08-06 22:39:14 +02:00
Stefan Hajnoczi
dae8796d00 docs: add lazy refcounts bit to qcow2 specification
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>
2012-08-06 22:39:14 +02:00