A basic set of qemu options is initialised in ./common:

export QEMU_OPTIONS="-nodefaults -machine accel=qtest"

However, two test cases (172 and 186) overwrite QEMU_OPTIONS and neglect

to manually set '-machine accel=qtest'. Add the missing option for 172.

186 probably only copied the code from 172, it doesn't actually need to

overwrite QEMU_OPTIONS, so remove that in 186.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>

Tested-by: Cornelia Huck <cohuck@redhat.com>

Reviewed-by: Cornelia Huck <cohuck@redhat.com>

---

tests/qemu-iotests/172 | 2 +-

tests/qemu-iotests/186 | 6 +++---

2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/tests/qemu-iotests/172 b/tests/qemu-iotests/172

index XXXXXXX..XXXXXXX 100755

--- a/tests/qemu-iotests/172

+++ b/tests/qemu-iotests/172

@@ -XXX,XX +XXX,XX @@ function do_run_qemu()

done

fi

echo quit

- ) | $QEMU -nographic -monitor stdio -serial none "$@"

+ ) | $QEMU -machine accel=qtest -nographic -monitor stdio -serial none "$@"

echo

}

diff --git a/tests/qemu-iotests/186 b/tests/qemu-iotests/186

index XXXXXXX..XXXXXXX 100755

--- a/tests/qemu-iotests/186

+++ b/tests/qemu-iotests/186

@@ -XXX,XX +XXX,XX @@ function do_run_qemu()

done

fi

echo quit

- ) | $QEMU -S -nodefaults -display none -device virtio-scsi-pci -monitor stdio "$@" 2>&1

+ ) | $QEMU -S -display none -device virtio-scsi-pci -monitor stdio "$@" 2>&1

echo

}

function check_info_block()

{

echo "info block" |

- QEMU_OPTIONS="" do_run_qemu "$@" | _filter_win32 | _filter_hmp |

- _filter_qemu | _filter_generated_node_ids

+ do_run_qemu "$@" | _filter_win32 | _filter_hmp | _filter_qemu |

+ _filter_generated_node_ids

}

--

2.13.5

From: Fam Zheng <famz@redhat.com>

It's not too surprising when a user specifies the backing file relative

to the current working directory instead of the top layer image. This

causes error when they differ. Though the error message has enough

information to infer the fact about the misunderstanding, it is better

if we document this explicitly, so that users don't have to learn from

mistakes.

Signed-off-by: Fam Zheng <famz@redhat.com>

Reviewed-by: Eric Blake <eblake@redhat.com>

Reviewed-by: Jeff Cody <jcody@redhat.com>

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>

Signed-off-by: Kevin Wolf <kwolf@redhat.com>

---

qemu-img.texi | 9 +++++++++

1 file changed, 9 insertions(+)

diff --git a/qemu-img.texi b/qemu-img.texi

index XXXXXXX..XXXXXXX 100644

--- a/qemu-img.texi

+++ b/qemu-img.texi

@@ -XXX,XX +XXX,XX @@ only the differences from @var{backing_file}. No size needs to be specified in

this case. @var{backing_file} will never be modified unless you use the

@code{commit} monitor command (or qemu-img commit).

+If a relative path name is given, the backing file is looked up relative to

+the directory containing @var{filename}.

+

Note that a given backing file will be opened to check that it is valid. Use

the @code{-u} option to enable unsafe backing file mode, which means that the

image will be created even if the associated backing file cannot be opened. A

@@ -XXX,XX +XXX,XX @@ created as a copy on write image of the specified base image; the

@var{backing_file} should have the same content as the input's base image,

however the path, image format, etc may differ.

+If a relative path name is given, the backing file is looked up relative to

+the directory containing @var{output_filename}.

+

If the @code{-n} option is specified, the target volume creation will be

skipped. This is useful for formats such as @code{rbd} if the target

volume has already been created with site specific options that cannot

@@ -XXX,XX +XXX,XX @@ The backing file is changed to @var{backing_file} and (if the image format of

string), then the image is rebased onto no backing file (i.e. it will exist

independently of any backing file).

+If a relative path name is given, the backing file is looked up relative to

+the directory containing @var{filename}.

+

@var{cache} specifies the cache mode to be used for @var{filename}, whereas

@var{src_cache} specifies the cache mode for reading backing files.

--

2.13.5

From: Fam Zheng <famz@redhat.com>

People get surprised when, after "qemu-img create -f raw /dev/sdX", they

still see qcow2 with "qemu-img info", if previously the bdev had a qcow2

header. While this is natural because raw doesn't need to write any

magic bytes during creation, hdev_create is free to clear out the first

sector to make sure the stale qcow2 header doesn't cause such confusion.

Signed-off-by: Fam Zheng <famz@redhat.com>

Signed-off-by: Kevin Wolf <kwolf@redhat.com>

---

block/file-posix.c | 10 ++++++++++

1 file changed, 10 insertions(+)

diff --git a/block/file-posix.c b/block/file-posix.c

index XXXXXXX..XXXXXXX 100644

--- a/block/file-posix.c

+++ b/block/file-posix.c

@@ -XXX,XX +XXX,XX @@ static int hdev_create(const char *filename, QemuOpts *opts,

ret = -ENOSPC;

}

+ if (!ret && total_size) {

+ uint8_t buf[BDRV_SECTOR_SIZE] = { 0 };

+ int64_t zero_size = MIN(BDRV_SECTOR_SIZE, total_size);

+ if (lseek(fd, 0, SEEK_SET) == -1) {

+ ret = -errno;

+ } else {

+ ret = qemu_write_full(fd, buf, zero_size);

+ ret = ret == zero_size ? 0 : -errno;

+ }

+ }

qemu_close(fd);

return ret;

}

--

2.13.5

From: Stefan Hajnoczi <stefanha@redhat.com>

Block driver documentation is available in qemu-doc.html. It would be

convenient to have documentation for formats, protocols, and filter

drivers in a man page.

Extract the relevant part of qemu-doc.html into a new file called

docs/qemu-block-drivers.texi. This file can also be built as a

stand-alone document (man, html, etc).

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

Signed-off-by: Kevin Wolf <kwolf@redhat.com>

---

Makefile | 6 +-

docs/qemu-block-drivers.texi | 804 +++++++++++++++++++++++++++++++++++++++++++

qemu-doc.texi | 781 +----------------------------------------

3 files changed, 810 insertions(+), 781 deletions(-)

create mode 100644 docs/qemu-block-drivers.texi

diff --git a/Makefile b/Makefile

index XXXXXXX..XXXXXXX 100644

--- a/Makefile

+++ b/Makefile

@@ -XXX,XX +XXX,XX @@ ifdef BUILD_DOCS

DOCS=qemu-doc.html qemu-doc.txt qemu.1 qemu-img.1 qemu-nbd.8 qemu-ga.8

DOCS+=docs/interop/qemu-qmp-ref.html docs/interop/qemu-qmp-ref.txt docs/interop/qemu-qmp-ref.7

DOCS+=docs/interop/qemu-ga-ref.html docs/interop/qemu-ga-ref.txt docs/interop/qemu-ga-ref.7

+DOCS+=docs/qemu-block-drivers.7

ifdef CONFIG_VIRTFS

DOCS+=fsdev/virtfs-proxy-helper.1

endif

@@ -XXX,XX +XXX,XX @@ distclean: clean

    rm -f docs/interop/qemu-qmp-ref.txt docs/interop/qemu-ga-ref.txt

    rm -f docs/interop/qemu-qmp-ref.pdf docs/interop/qemu-ga-ref.pdf

    rm -f docs/interop/qemu-qmp-ref.html docs/interop/qemu-ga-ref.html

+    rm -f docs/qemu-block-drivers.7

    for d in $(TARGET_DIRS); do \

    rm -rf $$d || exit 1 ; \

done

@@ -XXX,XX +XXX,XX @@ ifdef CONFIG_POSIX

    $(INSTALL_DATA) qemu.1 "$(DESTDIR)$(mandir)/man1"

    $(INSTALL_DIR) "$(DESTDIR)$(mandir)/man7"

    $(INSTALL_DATA) docs/interop/qemu-qmp-ref.7 "$(DESTDIR)$(mandir)/man7"

+    $(INSTALL_DATA) docs/qemu-block-drivers.7 "$(DESTDIR)$(mandir)/man7"

ifneq ($(TOOLS),)

    $(INSTALL_DATA) qemu-img.1 "$(DESTDIR)$(mandir)/man1"

    $(INSTALL_DIR) "$(DESTDIR)$(mandir)/man8"

@@ -XXX,XX +XXX,XX @@ qemu-img.1: qemu-img.texi qemu-option-trace.texi qemu-img-cmds.texi

fsdev/virtfs-proxy-helper.1: fsdev/virtfs-proxy-helper.texi

qemu-nbd.8: qemu-nbd.texi qemu-option-trace.texi

qemu-ga.8: qemu-ga.texi

+docs/qemu-block-drivers.7: docs/qemu-block-drivers.texi

html: qemu-doc.html docs/interop/qemu-qmp-ref.html docs/interop/qemu-ga-ref.html

info: qemu-doc.info docs/interop/qemu-qmp-ref.info docs/interop/qemu-ga-ref.info

@@ -XXX,XX +XXX,XX @@ txt: qemu-doc.txt docs/interop/qemu-qmp-ref.txt docs/interop/qemu-ga-ref.txt

qemu-doc.html qemu-doc.info qemu-doc.pdf qemu-doc.txt: \

    qemu-img.texi qemu-nbd.texi qemu-options.texi qemu-option-trace.texi \

    qemu-monitor.texi qemu-img-cmds.texi qemu-ga.texi \

-    qemu-monitor-info.texi

+    qemu-monitor-info.texi docs/qemu-block-drivers.texi

docs/interop/qemu-ga-ref.dvi docs/interop/qemu-ga-ref.html \

docs/interop/qemu-ga-ref.info docs/interop/qemu-ga-ref.pdf \

diff --git a/docs/qemu-block-drivers.texi b/docs/qemu-block-drivers.texi

new file mode 100644

index XXXXXXX..XXXXXXX

--- /dev/null

+++ b/docs/qemu-block-drivers.texi

@@ -XXX,XX +XXX,XX @@

+@c man begin SYNOPSIS

+QEMU block driver reference manual

+@c man end

+

+@c man begin DESCRIPTION

+

+@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.

+

+Supported options:

+@table @code

+@item preallocation

+Preallocation mode (allowed values: @code{off}, @code{falloc}, @code{full}).

+@code{falloc} mode preallocates space for image by calling posix_fallocate().

+@code{full} mode preallocates space for image by writing zeros to underlying

+storage.

+@end table

+

+@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), 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.

+@code{compat=1.1} enables image format extensions that only QEMU 1.1 and

+newer understand (this is the default). 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

+This option is deprecated and equivalent to @code{encrypt.format=aes}

+

+@item encrypt.format

+

+If this is set to @code{luks}, it requests that the qcow2 payload (not

+qcow2 header) be encrypted using the LUKS format. The passphrase to

+use to unlock the LUKS key slot is given by the @code{encrypt.key-secret}

+parameter. LUKS encryption parameters can be tuned with the other

+@code{encrypt.*} parameters.

+

+If this is set to @code{aes}, the image is encrypted with 128-bit AES-CBC.

+The encryption key is given by the @code{encrypt.key-secret} parameter.

+This encryption format is considered to be flawed by modern cryptography

+standards, suffering from a number of design problems:

+

+@itemize @minus

+@item The AES-CBC cipher is used with predictable initialization vectors based

+on the sector number. This makes it vulnerable to chosen plaintext attacks

+which can reveal the existence of encrypted data.

+@item The user passphrase is directly used as the encryption key. A poorly

+chosen or short passphrase will compromise the security of the encryption.

+@item In the event of the passphrase being compromised there is no way to

+change the passphrase to protect data in any qcow images. The files must

+be cloned, using a different encryption passphrase in the new file. The

+original file must then be securely erased using a program like shred,

+though even this is ineffective with many modern storage technologies.

+@end itemize

+

+The use of this is no longer supported in system emulators. Support only

+remains in the command line utilities, for the purposes of data liberation

+and interoperability with old versions of QEMU. The @code{luks} format

+should be used instead.

+

+@item encrypt.key-secret

+

+Provides the ID of a @code{secret} object that contains the passphrase

+(@code{encrypt.format=luks}) or encryption key (@code{encrypt.format=aes}).

+

+@item encrypt.cipher-alg

+

+Name of the cipher algorithm and key length. Currently defaults

+to @code{aes-256}. Only used when @code{encrypt.format=luks}.

+

+@item encrypt.cipher-mode

+

+Name of the encryption mode to use. Currently defaults to @code{xts}.

+Only used when @code{encrypt.format=luks}.

+

+@item encrypt.ivgen-alg

+

+Name of the initialization vector generator algorithm. Currently defaults

+to @code{plain64}. Only used when @code{encrypt.format=luks}.

+

+@item encrypt.ivgen-hash-alg

+

+Name of the hash algorithm to use with the initialization vector generator

+(if required). Defaults to @code{sha256}. Only used when @code{encrypt.format=luks}.

+

+@item encrypt.hash-alg

+

+Name of the hash algorithm to use for PBKDF algorithm

+Defaults to @code{sha256}. Only used when @code{encrypt.format=luks}.

+

+@item encrypt.iter-time

+

+Amount of time, in milliseconds, to use for PBKDF algorithm per key slot.

+Defaults to @code{2000}. Only used when @code{encrypt.format=luks}.

+

+@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: @code{off}, @code{metadata}, @code{falloc},

+@code{full}). An image with preallocated metadata is initially larger but can

+improve performance when the image needs to grow. @code{falloc} and @code{full}

+preallocations are like the same options of @code{raw} format, but sets up

+metadata also.

+

+@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.

+

+@item nocow

+If this option is set to @code{on}, it will turn off COW of the file. It's only

+valid on btrfs, no effect on other file systems.

+

+Btrfs has low performance when hosting a VM image file, even more when the guest

+on the VM also using btrfs as file system. Turning off COW is a way to mitigate

+this bad performance. Generally there are two ways to turn off COW on btrfs:

+a) Disable it by mounting with nodatacow, then all newly created files will be

+NOCOW. b) For an empty file, add the NOCOW file attribute. That's what this option

+does.

+

+Note: this option is only valid to new or empty files. If there is an existing

+file which is COW and has data blocks already, it couldn't be changed to NOCOW

+by setting @code{nocow=on}. One can issue @code{lsattr filename} to check if

+the NOCOW flag is set or not (Capital 'C' is NOCOW flag).

+

+@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

+This option is deprecated and equivalent to @code{encrypt.format=aes}

+

+@item encrypt.format

+If this is set to @code{aes}, the image is encrypted with 128-bit AES-CBC.

+The encryption key is given by the @code{encrypt.key-secret} parameter.

+This encryption format is considered to be flawed by modern cryptography

+standards, suffering from a number of design problems enumerated previously

+against the @code{qcow2} image format.

+

+The use of this is no longer supported in system emulators. Support only

+remains in the command line utilities, for the purposes of data liberation

+and interoperability with old versions of QEMU.

+

+Users requiring native encryption should use the @code{qcow2} format

+instead with @code{encrypt.format=luks}.

+

+@item encrypt.key-secret

+

+Provides the ID of a @code{secret} object that contains the encryption

+key (@code{encrypt.format=aes}).

+

+@end table

+

+@item luks

+

+LUKS v1 encryption format, compatible with Linux dm-crypt/cryptsetup

+

+Supported options:

+@table @code

+

+@item key-secret

+

+Provides the ID of a @code{secret} object that contains the passphrase.

+

+@item cipher-alg

+

+Name of the cipher algorithm and key length. Currently defaults

+to @code{aes-256}.

+

+@item cipher-mode

+

+Name of the encryption mode to use. Currently defaults to @code{xts}.

+

+@item ivgen-alg

+

+Name of the initialization vector generator algorithm. Currently defaults

+to @code{plain64}.

+

+@item ivgen-hash-alg

+

+Name of the hash algorithm to use with the initialization vector generator

+(if required). Defaults to @code{sha256}.

+

+@item hash-alg

+

+Name of the hash algorithm to use for PBKDF algorithm

+Defaults to @code{sha256}.

+

+@item iter-time

+

+Amount of time, in milliseconds, to use for PBKDF algorithm per key slot.

+Defaults to @code{2000}.

+

+@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 hwversion

+Specify vmdk virtual hardware version. Compat6 flag cannot be enabled

+if hwversion is specified.

+@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

+

+@item VHDX

+Hyper-V compatible image format (VHDX).

+Supported options:

+@table @code

+@item subformat

+Specifies which VHDX subformat to use. Valid options are

+@code{dynamic} (default) and @code{fixed}.

+@item block_state_zero

+Force use of payload blocks of type 'ZERO'. Can be set to @code{on} (default)

+or @code{off}. When set to @code{off}, new blocks will be created as

+@code{PAYLOAD_BLOCK_NOT_PRESENT}, which means parsers are free to return

+arbitrary data for those blocks. Do not set to @code{off} when using

+@code{qemu-img convert} with @code{subformat=dynamic}.

+@item block_size

+Block size; min 1 MB, max 256 MB. 0 means auto-calculate based on image size.

+@item log_size

+Log size; min 1 MB.

+@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

+

+In addition to disk image files, QEMU can directly access host

+devices. We describe here the usage for QEMU version >= 0.8.3.

+

+@subsubsection Linux

+

+On Linux, you can directly use the host device filename instead of a

+disk image filename provided you have enough privileges to access

+it. For example, use @file{/dev/cdrom} to access to the CDROM.

+

+@table @code

+@item CD

+You can specify a CDROM device even if no CDROM is loaded. QEMU has

+specific code to detect CDROM insertion or removal. CDROM ejection by

+the guest OS is supported. Currently only data CDs are supported.

+@item Floppy

+You can specify a floppy device even if no floppy is loaded. Floppy

+removal is currently not detected accurately (if you change floppy

+without doing floppy access while the floppy is not loaded, the guest

+OS will think that the same floppy is loaded).

+Use of the host's floppy device is deprecated, and support for it will

+be removed in a future release.

+@item Hard disks

+Hard disks can be used. Normally you must specify the whole disk

+(@file{/dev/hdb} instead of @file{/dev/hdb1}) so that the guest OS can

+see it as a partitioned disk. WARNING: unless you know what you do, it

+is better to only make READ-ONLY accesses to the hard disk otherwise

+you may corrupt your host data (use the @option{-snapshot} command

+line option or modify the device permissions accordingly).

+@end table

+

+@subsubsection Windows

+

+@table @code

+@item CD

+The preferred syntax is the drive letter (e.g. @file{d:}). The

+alternate syntax @file{\\.\d:} is supported. @file{/dev/cdrom} is

+supported as an alias to the first CDROM drive.

+

+Currently there is no specific code to handle removable media, so it

+is better to use the @code{change} or @code{eject} monitor commands to

+change or eject media.

+@item Hard disks

+Hard disks can be used with the syntax: @file{\\.\PhysicalDrive@var{N}}

+where @var{N} is the drive number (0 is the first hard disk).

+

+WARNING: unless you know what you do, it is better to only make

+READ-ONLY accesses to the hard disk otherwise you may corrupt your

+host data (use the @option{-snapshot} command line so that the

+modifications are written in a temporary file).

+@end table

+

+

+@subsubsection Mac OS X

+

+@file{/dev/cdrom} is an alias to the first CDROM.

+

+Currently there is no specific code to handle removable media, so it

+is better to use the @code{change} or @code{eject} monitor commands to

+change or eject media.

+

+@node disk_images_fat_images

+@subsection Virtual FAT disk images

+

+QEMU can automatically create a virtual FAT disk image from a

+directory tree. In order to use it, just type:

+

+@example

+qemu-system-i386 linux.img -hdb fat:/my_directory

+@end example

+

+Then you access access to all the files in the @file{/my_directory}

+directory without having to copy them in a disk image or to export

+them via SAMBA or NFS. The default access is @emph{read-only}.

+

+Floppies can be emulated with the @code{:floppy:} option:

+

+@example

+qemu-system-i386 linux.img -fda fat:floppy:/my_directory

+@end example

+

+A read/write support is available for testing (beta stage) with the

+@code{:rw:} option:

+

+@example

+qemu-system-i386 linux.img -fda fat:floppy:rw:/my_directory

+@end example

+

+What you should @emph{never} do:

+@itemize

+@item use non-ASCII filenames ;

+@item use "-snapshot" together with ":rw:" ;

+@item expect it to work when loadvm'ing ;

+@item write to the FAT directory on the host system while accessing it with the guest system.

+@end itemize

+

+@node disk_images_nbd

+@subsection NBD access

+

+QEMU can access directly to block device exported using the Network Block Device

+protocol.

+

+@example

+qemu-system-i386 linux.img -hdb nbd://my_nbd_server.mydomain.org:1024/

+@end example

+

+If the NBD server is located on the same host, you can use an unix socket instead

+of an inet socket:

+

+@example

+qemu-system-i386 linux.img -hdb nbd+unix://?socket=/tmp/my_socket

+@end example

+

+In this case, the block device must be exported using qemu-nbd:

+

+@example

+qemu-nbd --socket=/tmp/my_socket my_disk.qcow2

+@end example

+

+The use of qemu-nbd allows sharing of a disk between several guests:

+@example

+qemu-nbd --socket=/tmp/my_socket --share=2 my_disk.qcow2

+@end example

+

+@noindent

+and then you can use it with two guests:

+@example

+qemu-system-i386 linux1.img -hdb nbd+unix://?socket=/tmp/my_socket

+qemu-system-i386 linux2.img -hdb nbd+unix://?socket=/tmp/my_socket

+@end example

+

+If the nbd-server uses named exports (supported since NBD 2.9.18, or with QEMU's

+own embedded NBD server), you must specify an export name in the URI:

+@example

+qemu-system-i386 -cdrom nbd://localhost/debian-500-ppc-netinst

+qemu-system-i386 -cdrom nbd://localhost/openSUSE-11.1-ppc-netinst

+@end example

+

+The URI syntax for NBD is supported since QEMU 1.3. An alternative syntax is

+also available. Here are some example of the older syntax:

+@example

+qemu-system-i386 linux.img -hdb nbd:my_nbd_server.mydomain.org:1024

+qemu-system-i386 linux2.img -hdb nbd:unix:/tmp/my_socket

+qemu-system-i386 -cdrom nbd:localhost:10809:exportname=debian-500-ppc-netinst

+@end example

+

+@node disk_images_sheepdog

+@subsection Sheepdog disk images

+

+Sheepdog is a distributed storage system for QEMU. It provides highly

+available block level storage volumes that can be attached to

+QEMU-based virtual machines.

+

+You can create a Sheepdog disk image with the command:

+@example

+qemu-img create sheepdog:///@var{image} @var{size}

+@end example

+where @var{image} is the Sheepdog image name and @var{size} is its

+size.

+

+To import the existing @var{filename} to Sheepdog, you can use a

+convert command.

+@example

+qemu-img convert @var{filename} sheepdog:///@var{image}

+@end example

+

+You can boot from the Sheepdog disk image with the command:

+@example

+qemu-system-i386 sheepdog:///@var{image}

+@end example

+

+You can also create a snapshot of the Sheepdog image like qcow2.

+@example

+qemu-img snapshot -c @var{tag} sheepdog:///@var{image}

+@end example

+where @var{tag} is a tag name of the newly created snapshot.

+

+To boot from the Sheepdog snapshot, specify the tag name of the

+snapshot.

+@example

+qemu-system-i386 sheepdog:///@var{image}#@var{tag}

+@end example

+

+You can create a cloned image from the existing snapshot.

+@example

+qemu-img create -b sheepdog:///@var{base}#@var{tag} sheepdog:///@var{image}

+@end example

+where @var{base} is a image name of the source snapshot and @var{tag}

+is its tag name.

+

+You can use an unix socket instead of an inet socket:

+

+@example

+qemu-system-i386 sheepdog+unix:///@var{image}?socket=@var{path}

+@end example

+

+If the Sheepdog daemon doesn't run on the local host, you need to

+specify one of the Sheepdog servers to connect to.

+@example

+qemu-img create sheepdog://@var{hostname}:@var{port}/@var{image} @var{size}

+qemu-system-i386 sheepdog://@var{hostname}:@var{port}/@var{image}

+@end example

+

+@node disk_images_iscsi

+@subsection iSCSI LUNs

+

+iSCSI is a popular protocol used to access SCSI devices across a computer

+network.

+

+There are two different ways iSCSI devices can be used by QEMU.

+

+The first method is to mount the iSCSI LUN on the host, and make it appear as

+any other ordinary SCSI device on the host and then to access this device as a

+/dev/sd device from QEMU. How to do this differs between host OSes.

+

+The second method involves using the iSCSI initiator that is built into

+QEMU. This provides a mechanism that works the same way regardless of which

+host OS you are running QEMU on. This section will describe this second method

+of using iSCSI together with QEMU.

+

+In QEMU, iSCSI devices are described using special iSCSI URLs

+

+@example

+URL syntax:

+iscsi://[<username>[%<password>]@@]<host>[:<port>]/<target-iqn-name>/<lun>

+@end example

+

+Username and password are optional and only used if your target is set up

+using CHAP authentication for access control.

+Alternatively the username and password can also be set via environment

+variables to have these not show up in the process list

+

+@example

+export LIBISCSI_CHAP_USERNAME=<username>

+export LIBISCSI_CHAP_PASSWORD=<password>

+iscsi://<host>/<target-iqn-name>/<lun>

+@end example

+

+Various session related parameters can be set via special options, either

+in a configuration file provided via '-readconfig' or directly on the

+command line.

+

+If the initiator-name is not specified qemu will use a default name

+of 'iqn.2008-11.org.linux-kvm[:<uuid>'] where <uuid> is the UUID of the

+virtual machine. If the UUID is not specified qemu will use

+'iqn.2008-11.org.linux-kvm[:<name>'] where <name> is the name of the

+virtual machine.

+

+@example

+Setting a specific initiator name to use when logging in to the target

+-iscsi initiator-name=iqn.qemu.test:my-initiator

+@end example

+

+@example

+Controlling which type of header digest to negotiate with the target

+-iscsi header-digest=CRC32C|CRC32C-NONE|NONE-CRC32C|NONE

+@end example

+

+These can also be set via a configuration file

+@example

+[iscsi]

+ user = "CHAP username"

+ password = "CHAP password"

+ initiator-name = "iqn.qemu.test:my-initiator"

+ # header digest is one of CRC32C|CRC32C-NONE|NONE-CRC32C|NONE

+ header-digest = "CRC32C"

+@end example

+

+

+Setting the target name allows different options for different targets

+@example

+[iscsi "iqn.target.name"]

+ user = "CHAP username"

+ password = "CHAP password"

+ initiator-name = "iqn.qemu.test:my-initiator"

+ # header digest is one of CRC32C|CRC32C-NONE|NONE-CRC32C|NONE

+ header-digest = "CRC32C"

+@end example

+

+

+Howto use a configuration file to set iSCSI configuration options:

+@example

+cat >iscsi.conf <<EOF

+[iscsi]

+ user = "me"

+ password = "my password"

+ initiator-name = "iqn.qemu.test:my-initiator"

+ header-digest = "CRC32C"

+EOF

+

+qemu-system-i386 -drive file=iscsi://127.0.0.1/iqn.qemu.test/1 \

+ -readconfig iscsi.conf

+@end example

+

+

+Howto set up a simple iSCSI target on loopback and accessing it via QEMU:

+@example

+This example shows how to set up an iSCSI target with one CDROM and one DISK

+using the Linux STGT software target. This target is available on Red Hat based

+systems as the package 'scsi-target-utils'.

+

+tgtd --iscsi portal=127.0.0.1:3260

+tgtadm --lld iscsi --op new --mode target --tid 1 -T iqn.qemu.test

+tgtadm --lld iscsi --mode logicalunit --op new --tid 1 --lun 1 \

+ -b /IMAGES/disk.img --device-type=disk

+tgtadm --lld iscsi --mode logicalunit --op new --tid 1 --lun 2 \

+ -b /IMAGES/cd.iso --device-type=cd

+tgtadm --lld iscsi --op bind --mode target --tid 1 -I ALL

+

+qemu-system-i386 -iscsi initiator-name=iqn.qemu.test:my-initiator \

+ -boot d -drive file=iscsi://127.0.0.1/iqn.qemu.test/1 \

+ -cdrom iscsi://127.0.0.1/iqn.qemu.test/2

+@end example

+

+@node disk_images_gluster

+@subsection GlusterFS disk images

+

+GlusterFS is a user space distributed file system.

+

+You can boot from the GlusterFS disk image with the command:

+@example

+URI:

+qemu-system-x86_64 -drive file=gluster[+@var{type}]://[@var{host}[:@var{port}]]/@var{volume}/@var{path}

+ [?socket=...][,file.debug=9][,file.logfile=...]

+

+JSON:

+qemu-system-x86_64 'json:@{"driver":"qcow2",

+ "file":@{"driver":"gluster",

+ "volume":"testvol","path":"a.img","debug":9,"logfile":"...",

+ "server":[@{"type":"tcp","host":"...","port":"..."@},

+ @{"type":"unix","socket":"..."@}]@}@}'

+@end example

+

+@var{gluster} is the protocol.

+

+@var{type} specifies the transport type used to connect to gluster

+management daemon (glusterd). Valid transport types are

+tcp and unix. In the URI form, if a transport type isn't specified,

+then tcp type is assumed.

+

+@var{host} specifies the server where the volume file specification for

+the given volume resides. This can be either a hostname or an ipv4 address.

+If transport type is unix, then @var{host} field should not be specified.

+Instead @var{socket} field needs to be populated with the path to unix domain

+socket.

+

+@var{port} is the port number on which glusterd is listening. This is optional

+and if not specified, it defaults to port 24007. If the transport type is unix,

+then @var{port} should not be specified.

+

+@var{volume} is the name of the gluster volume which contains the disk image.

+

+@var{path} is the path to the actual disk image that resides on gluster volume.

+

+@var{debug} is the logging level of the gluster protocol driver. Debug levels

+are 0-9, with 9 being the most verbose, and 0 representing no debugging output.

+The default level is 4. The current logging levels defined in the gluster source

+are 0 - None, 1 - Emergency, 2 - Alert, 3 - Critical, 4 - Error, 5 - Warning,

+6 - Notice, 7 - Info, 8 - Debug, 9 - Trace

+

+@var{logfile} is a commandline option to mention log file path which helps in

+logging to the specified file and also help in persisting the gfapi logs. The

+default is stderr.

+

+

+

+

+You can create a GlusterFS disk image with the command:

+@example

+qemu-img create gluster://@var{host}/@var{volume}/@var{path} @var{size}

+@end example

+

+Examples

+@example

+qemu-system-x86_64 -drive file=gluster://1.2.3.4/testvol/a.img

+qemu-system-x86_64 -drive file=gluster+tcp://1.2.3.4/testvol/a.img

+qemu-system-x86_64 -drive file=gluster+tcp://1.2.3.4:24007/testvol/dir/a.img

+qemu-system-x86_64 -drive file=gluster+tcp://[1:2:3:4:5:6:7:8]/testvol/dir/a.img

+qemu-system-x86_64 -drive file=gluster+tcp://[1:2:3:4:5:6:7:8]:24007/testvol/dir/a.img

+qemu-system-x86_64 -drive file=gluster+tcp://server.domain.com:24007/testvol/dir/a.img

+qemu-system-x86_64 -drive file=gluster+unix:///testvol/dir/a.img?socket=/tmp/glusterd.socket

+qemu-system-x86_64 -drive file=gluster+rdma://1.2.3.4:24007/testvol/a.img

+qemu-system-x86_64 -drive file=gluster://1.2.3.4/testvol/a.img,file.debug=9,file.logfile=/var/log/qemu-gluster.log

+qemu-system-x86_64 'json:@{"driver":"qcow2",

+ "file":@{"driver":"gluster",

+ "volume":"testvol","path":"a.img",

+ "debug":9,"logfile":"/var/log/qemu-gluster.log",

+ "server":[@{"type":"tcp","host":"1.2.3.4","port":24007@},

+ @{"type":"unix","socket":"/var/run/glusterd.socket"@}]@}@}'

+qemu-system-x86_64 -drive driver=qcow2,file.driver=gluster,file.volume=testvol,file.path=/path/a.img,

+ file.debug=9,file.logfile=/var/log/qemu-gluster.log,

+ file.server.0.type=tcp,file.server.0.host=1.2.3.4,file.server.0.port=24007,

+ file.server.1.type=unix,file.server.1.socket=/var/run/glusterd.socket

+@end example

+

+@node disk_images_ssh

+@subsection Secure Shell (ssh) disk images

+

+You can access disk images located on a remote ssh server

+by using the ssh protocol:

+

+@example

+qemu-system-x86_64 -drive file=ssh://[@var{user}@@]@var{server}[:@var{port}]/@var{path}[?host_key_check=@var{host_key_check}]

+@end example

+

+Alternative syntax using properties:

+

+@example

+qemu-system-x86_64 -drive file.driver=ssh[,file.user=@var{user}],file.host=@var{server}[,file.port=@var{port}],file.path=@var{path}[,file.host_key_check=@var{host_key_check}]

+@end example

+

+@var{ssh} is the protocol.

+

+@var{user} is the remote user. If not specified, then the local

+username is tried.

+

+@var{server} specifies the remote ssh server. Any ssh server can be

+used, but it must implement the sftp-server protocol. Most Unix/Linux

+systems should work without requiring any extra configuration.

+

+@var{port} is the port number on which sshd is listening. By default

+the standard ssh port (22) is used.

+

+@var{path} is the path to the disk image.

+

+The optional @var{host_key_check} parameter controls how the remote

+host's key is checked. The default is @code{yes} which means to use

+the local @file{.ssh/known_hosts} file. Setting this to @code{no}

+turns off known-hosts checking. Or you can check that the host key

+matches a specific fingerprint:

+@code{host_key_check=md5:78:45:8e:14:57:4f:d5:45:83:0a:0e:f3:49:82:c9:c8}

+(@code{sha1:} can also be used as a prefix, but note that OpenSSH

+tools only use MD5 to print fingerprints).

+

+Currently authentication must be done using ssh-agent. Other

+authentication methods may be supported in future.

+

+Note: Many ssh servers do not support an @code{fsync}-style operation.

+The ssh driver cannot guarantee that disk flush requests are

+obeyed, and this causes a risk of disk corruption if the remote

+server or network goes down during writes. The driver will

+print a warning when @code{fsync} is not supported:

+

+warning: ssh server @code{ssh.example.com:22} does not support fsync

+

+With sufficiently new versions of libssh2 and OpenSSH, @code{fsync} is

+supported.

+

+@c man end

+

+@ignore

+

+@setfilename qemu-block-drivers

+@settitle QEMU block drivers reference

+

+@c man begin SEEALSO

+The HTML documentation of QEMU for more precise information and Linux

+user mode emulator invocation.

+@c man end

+

+@c man begin AUTHOR

+Fabrice Bellard and the QEMU Project developers

+@c man end

+

+@end ignore

diff --git a/qemu-doc.texi b/qemu-doc.texi

index XXXXXXX..XXXXXXX 100644

--- a/qemu-doc.texi

+++ b/qemu-doc.texi

@@ -XXX,XX +XXX,XX @@ 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.

-

-Supported options:

-@table @code

-@item preallocation

-Preallocation mode (allowed values: @code{off}, @code{falloc}, @code{full}).

-@code{falloc} mode preallocates space for image by calling posix_fallocate().

-@code{full} mode preallocates space for image by writing zeros to underlying

-storage.

-@end table

-

-@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), 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.

-@code{compat=1.1} enables image format extensions that only QEMU 1.1 and

-newer understand (this is the default). 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

-This option is deprecated and equivalent to @code{encrypt.format=aes}

-

-@item encrypt.format

-

-If this is set to @code{luks}, it requests that the qcow2 payload (not

-qcow2 header) be encrypted using the LUKS format. The passphrase to

-use to unlock the LUKS key slot is given by the @code{encrypt.key-secret}

-parameter. LUKS encryption parameters can be tuned with the other

-@code{encrypt.*} parameters.

-

-If this is set to @code{aes}, the image is encrypted with 128-bit AES-CBC.

-The encryption key is given by the @code{encrypt.key-secret} parameter.

-This encryption format is considered to be flawed by modern cryptography

-standards, suffering from a number of design problems:

-

-@itemize @minus

-@item The AES-CBC cipher is used with predictable initialization vectors based

-on the sector number. This makes it vulnerable to chosen plaintext attacks

-which can reveal the existence of encrypted data.

-@item The user passphrase is directly used as the encryption key. A poorly

-chosen or short passphrase will compromise the security of the encryption.

-@item In the event of the passphrase being compromised there is no way to

-change the passphrase to protect data in any qcow images. The files must

-be cloned, using a different encryption passphrase in the new file. The

-original file must then be securely erased using a program like shred,

-though even this is ineffective with many modern storage technologies.

-@end itemize

-

-The use of this is no longer supported in system emulators. Support only

-remains in the command line utilities, for the purposes of data liberation

-and interoperability with old versions of QEMU. The @code{luks} format

-should be used instead.

-

-@item encrypt.key-secret

-

-Provides the ID of a @code{secret} object that contains the passphrase

-(@code{encrypt.format=luks}) or encryption key (@code{encrypt.format=aes}).

-

-@item encrypt.cipher-alg

-

-Name of the cipher algorithm and key length. Currently defaults