Re: [PATCH 1/3] qemu-nbd: Convert invocation documentation to rST

[Alex Bennée]

Peter Maydell <address@hidden> writes:

> The qemu-nbd documentation is currently in qemu-nbd.texi in Texinfo
> format, which we present to the user as:
>  * a qemu-nbd manpage
>  * a section of the main qemu-doc HTML documentation
>
> Convert the documentation to rST format, and present it to the user as:
>  * a qemu-nbd manpage
>  * part of the interop/ Sphinx manual
>
> This follows the same pattern as commit 27a296fce982 did for the
> qemu-ga manpage.
>
> All the content of the old manpage is retained, except that I have
> dropped the "This is free software; see the source for copying
> conditions.  There is NO warranty..." text that was in the old AUTHOR
> section; Sphinx's manpage builder doesn't expect that much text in
> the AUTHOR section, and since none of our other manpages have it it
> seems easiest to delete it rather than try to figure out where else
> in the manpage to put it.
>
> The only other textual change is that I have had to give the
> --nocache option its own description ("Equivalent to --cache=none")
> because Sphinx doesn't have an equivalent of using item/itemx
> to share a description between two options.
>
> Some minor aspects of the formatting have changed, to suit what is
> easiest for Sphinx to output. (The most notable is that Sphinx
> option section option syntax doesn't support '--option foo=bar'
> with bar underlined rather than bold, so we have to switch to
> '--option foo=BAR' instead.)
>
> The contents of qemu-option-trace.texi are now duplicated in
> docs/interop/qemu-option-trace.rst.inc, until such time as we complete
> the conversion of the other files which use it; since it has had only
> 3 changes in 3 years, this shouldn't be too awkward a burden.
> (We use .rst.inc because if this file fragment has a .rst extension
> then Sphinx complains about not seeing it in a toctree.)
>
> Signed-off-by: Peter Maydell <address@hidden>

Reviewed-by: Alex Bennée <address@hidden>
Tested-by: Alex Bennée <address@hidden>

> ---
> Another step forward for https://wiki.qemu.org/Features/Documentation
> (this is part of step 3 in the 'transition plan').
>
> v1->v2:
>  * avoided some long lines in the Makefile
> ---
>  Makefile                               |  16 +-
>  MAINTAINERS                            |   1 +
>  docs/interop/conf.py                   |   4 +-
>  docs/interop/index.rst                 |   1 +
>  docs/interop/qemu-nbd.rst              | 263 +++++++++++++++++++++++++
>  docs/interop/qemu-option-trace.rst.inc |  30 +++
>  qemu-doc.texi                          |   6 -
>  qemu-nbd.texi                          | 214 --------------------
>  qemu-option-trace.texi                 |   4 +
>  9 files changed, 313 insertions(+), 226 deletions(-)
>  create mode 100644 docs/interop/qemu-nbd.rst
>  create mode 100644 docs/interop/qemu-option-trace.rst.inc
>  delete mode 100644 qemu-nbd.texi
>
> diff --git a/Makefile b/Makefile
> index afa5cb6548d..7a8a50d8700 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -339,7 +339,9 @@ MANUAL_BUILDDIR := docs
>  endif
>  
>  ifdef BUILD_DOCS
> -DOCS=qemu-doc.html qemu-doc.txt qemu.1 qemu-img.1 qemu-nbd.8 
> $(MANUAL_BUILDDIR)/interop/qemu-ga.8
> +DOCS=qemu-doc.html qemu-doc.txt qemu.1 qemu-img.1
> +DOCS+=$(MANUAL_BUILDDIR)/interop/qemu-nbd.8
> +DOCS+=$(MANUAL_BUILDDIR)/interop/qemu-ga.8
>  DOCS+=docs/interop/qemu-qmp-ref.html docs/interop/qemu-qmp-ref.txt 
> docs/interop/qemu-qmp-ref.7
>  DOCS+=docs/interop/qemu-ga-ref.html docs/interop/qemu-ga-ref.txt 
> docs/interop/qemu-ga-ref.7
>  DOCS+=docs/qemu-block-drivers.7
> @@ -829,7 +831,7 @@ ifdef CONFIG_POSIX
>  ifeq ($(CONFIG_TOOLS),y)
>       $(INSTALL_DATA) qemu-img.1 "$(DESTDIR)$(mandir)/man1"
>       $(INSTALL_DIR) "$(DESTDIR)$(mandir)/man8"
> -     $(INSTALL_DATA) qemu-nbd.8 "$(DESTDIR)$(mandir)/man8"
> +     $(INSTALL_DATA) $(MANUAL_BUILDDIR)/interop/qemu-nbd.8 
> "$(DESTDIR)$(mandir)/man8"
>  endif
>  ifdef CONFIG_TRACE_SYSTEMTAP
>       $(INSTALL_DATA) scripts/qemu-trace-stap.1 "$(DESTDIR)$(mandir)/man1"
> @@ -1007,7 +1009,9 @@ sphinxdocs: $(MANUAL_BUILDDIR)/devel/index.html 
> $(MANUAL_BUILDDIR)/interop/index
>  # a single doctree: https://github.com/sphinx-doc/sphinx/issues/2946
>  build-manual = $(call quiet-command,CONFDIR="$(qemu_confdir)" sphinx-build 
> $(if $(V),,-q) -W -b $2 -D version=$(VERSION) -D release="$(FULL_VERSION)" -d 
> .doctrees/$1-$2 $(SRC_PATH)/docs/$1 $(MANUAL_BUILDDIR)/$1 
> ,"SPHINX","$(MANUAL_BUILDDIR)/$1")
>  # We assume all RST files in the manual's directory are used in it
> -manual-deps = $(wildcard $(SRC_PATH)/docs/$1/*.rst) 
> $(SRC_PATH)/docs/$1/conf.py $(SRC_PATH)/docs/conf.py
> +manual-deps = $(wildcard $(SRC_PATH)/docs/$1/*.rst) \
> +              $(wildcard $(SRC_PATH)/docs/$1/*.rst.inc) \
> +              $(SRC_PATH)/docs/$1/conf.py $(SRC_PATH)/docs/conf.py
>  
>  $(MANUAL_BUILDDIR)/devel/index.html: $(call manual-deps,devel)
>       $(call build-manual,devel,html)
> @@ -1021,6 +1025,9 @@ $(MANUAL_BUILDDIR)/specs/index.html: $(call 
> manual-deps,specs)
>  $(MANUAL_BUILDDIR)/interop/qemu-ga.8: $(call manual-deps,interop)
>       $(call build-manual,interop,man)
>  
> +$(MANUAL_BUILDDIR)/interop/qemu-nbd.8: $(call manual-deps,interop)
> +     $(call build-manual,interop,man)
> +
>  $(MANUAL_BUILDDIR)/index.html: $(SRC_PATH)/docs/index.html.in qemu-version.h
>       $(call quiet-command, sed "s|@@VERSION@@|${VERSION}|g" $< >$@, \
>               "GEN","$@")
> @@ -1047,7 +1054,6 @@ qemu.1: qemu-doc.texi qemu-options.texi 
> qemu-monitor.texi qemu-monitor-info.texi
>  qemu.1: qemu-option-trace.texi
>  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
>  docs/qemu-block-drivers.7: docs/qemu-block-drivers.texi
>  docs/qemu-cpu-models.7: docs/qemu-cpu-models.texi
>  scripts/qemu-trace-stap.1: scripts/qemu-trace-stap.texi
> @@ -1058,7 +1064,7 @@ pdf: qemu-doc.pdf docs/interop/qemu-qmp-ref.pdf 
> docs/interop/qemu-ga-ref.pdf
>  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-img.texi qemu-options.texi \
>       qemu-tech.texi qemu-option-trace.texi \
>       qemu-deprecated.texi qemu-monitor.texi qemu-img-cmds.texi \
>       qemu-monitor-info.texi docs/qemu-block-drivers.texi \
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 483edfbc0b5..bfb6a9ba584 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -2503,6 +2503,7 @@ F: include/block/nbd*
>  F: qemu-nbd.*
>  F: blockdev-nbd.c
>  F: docs/interop/nbd.txt
> +F: docs/interop/qemu-nbd.rst
>  T: git https://repo.or.cz/qemu/ericb.git nbd
>  
>  NFS
> diff --git a/docs/interop/conf.py b/docs/interop/conf.py
> index e87b8c22bec..40b1ad811de 100644
> --- a/docs/interop/conf.py
> +++ b/docs/interop/conf.py
> @@ -18,5 +18,7 @@ html_theme_options['description'] = u'System Emulation 
> Management and Interopera
>  # (source start file, name, description, authors, manual section).
>  man_pages = [
>      ('qemu-ga', 'qemu-ga', u'QEMU Guest Agent',
> -     ['Michael Roth <address@hidden>'], 8)
> +     ['Michael Roth <address@hidden>'], 8),
> +    ('qemu-nbd', 'qemu-nbd', u'QEMU Disk Network Block Device Server',
> +     ['Anthony Liguori <address@hidden>'], 8)
>  ]
> diff --git a/docs/interop/index.rst b/docs/interop/index.rst
> index 049387ac6de..c28f7785a55 100644
> --- a/docs/interop/index.rst
> +++ b/docs/interop/index.rst
> @@ -18,5 +18,6 @@ Contents:
>     live-block-operations
>     pr-helper
>     qemu-ga
> +   qemu-nbd
>     vhost-user
>     vhost-user-gpu
> diff --git a/docs/interop/qemu-nbd.rst b/docs/interop/qemu-nbd.rst
> new file mode 100644
> index 00000000000..873bb9e17d5
> --- /dev/null
> +++ b/docs/interop/qemu-nbd.rst
> @@ -0,0 +1,263 @@
> +QEMU Disk Network Block Device Server
> +=====================================
> +
> +Synopsis
> +--------
> +
> +**qemu-nbd** [*OPTION*]... *filename*
> +
> +**qemu-nbd** -L [*OPTION*]...
> +
> +**qemu-nbd** -d *dev*
> +
> +Description
> +-----------
> +
> +Export a QEMU disk image using the NBD protocol.
> +
> +Other uses:
> +
> +- Bind a /dev/nbdX block device to a QEMU server (on Linux).
> +- As a client to query exports of a remote NBD server.
> +
> +Options
> +-------
> +
> +.. program:: qemu-nbd
> +
> +*filename* is a disk image filename, or a set of block
> +driver options if ``--image-opts`` is specified.
> +
> +*dev* is an NBD device.
> +
> +.. option:: --object type,id=ID,...props...
> +
> +  Define a new instance of the *type* object class identified by *ID*.
> +  See the :manpage:`qemu(1)` manual page for full details of the properties
> +  supported. The common object types that it makes sense to define are the
> +  ``secret`` object, which is used to supply passwords and/or encryption
> +  keys, and the ``tls-creds`` object, which is used to supply TLS
> +  credentials for the qemu-nbd server or client.
> +
> +.. option:: -p, --port=PORT
> +
> +  TCP port to listen on as a server, or connect to as a client
> +  (default ``10809``).
> +
> +.. option:: -o, --offset=OFFSET
> +
> +  The offset into the image.
> +
> +.. option:: -b, --bind=IFACE
> +
> +  The interface to bind to as a server, or connect to as a client
> +  (default ``0.0.0.0``).
> +
> +.. option:: -k, --socket=PATH
> +
> +  Use a unix socket with path *PATH*.
> +
> +.. option:: --image-opts
> +
> +  Treat *filename* as a set of image options, instead of a plain
> +  filename. If this flag is specified, the ``-f`` flag should
> +  not be used, instead the :option:`format=` option should be set.
> +
> +.. option:: -f, --format=FMT
> +
> +  Force the use of the block driver for format *FMT* instead of
> +  auto-detecting.
> +
> +.. option:: -r, --read-only
> +
> +  Export the disk as read-only.
> +
> +.. option:: -P, --partition=NUM
> +
> +  Deprecated: Only expose MBR partition *NUM*.  Understands physical
> +  partitions 1-4 and logical partition 5. New code should instead use
> +  :option:`--image-opts` with the raw driver wrapping a subset of the
> +  original image.
> +
> +.. option:: -B, --bitmap=NAME
> +
> +  If *filename* has a qcow2 persistent bitmap *NAME*, expose
> +  that bitmap via the ``qemu:dirty-bitmap:NAME`` context
> +  accessible through NBD_OPT_SET_META_CONTEXT.
> +
> +.. option:: -s, --snapshot
> +
> +  Use *filename* as an external snapshot, create a temporary
> +  file with ``backing_file=``\ *filename*, redirect the write to
> +  the temporary one.
> +
> +.. option:: -l, --load-snapshot=SNAPSHOT_PARAM
> +
> +  Load an internal snapshot inside *filename* and export it
> +  as an read-only device, SNAPSHOT_PARAM format is
> +  ``snapshot.id=[ID],snapshot.name=[NAME]`` or ``[ID_OR_NAME]``
> +
> +.. option:: --cache=CACHE
> +
> +  The cache mode to be used with the file.  See the documentation of
> +  the emulator's ``-drive cache=...`` option for allowed values.
> +
> +.. option:: -n, --nocache
> +
> +  Equivalent to :option:`--cache=none`.
> +
> +.. option:: --aio=AIO
> +
> +  Set the asynchronous I/O mode between ``threads`` (the default)
> +  and ``native`` (Linux only).
> +
> +.. option:: --discard=DISCARD
> +
> +  Control whether ``discard`` (also known as ``trim`` or ``unmap``)
> +  requests are ignored or passed to the filesystem. *DISCARD* is one of
> +  ``ignore`` (or ``off``), ``unmap`` (or ``on``).  The default is
> +  ``ignore``.
> +
> +.. option:: --detect-zeroes=DETECT_ZEROES
> +
> +  Control the automatic conversion of plain zero writes by the OS to
> +  driver-specific optimized zero write commands.  *DETECT_ZEROES* is one of
> +  ``off``, ``on``, or ``unmap``.  ``unmap``
> +  converts a zero write to an unmap operation and can only be used if
> +  *DISCARD* is set to ``unmap``.  The default is ``off``.
> +
> +.. option:: -c, --connect=DEV
> +
> +  Connect *filename* to NBD device *DEV* (Linux only).
> +
> +.. option:: -d, --disconnect
> +
> +  Disconnect the device *DEV* (Linux only).
> +
> +.. option:: -e, --shared=NUM
> +
> +  Allow up to *NUM* clients to share the device (default
> +  ``1``). Safe for readers, but for now, consistency is not
> +  guaranteed between multiple writers.
> +
> +.. option:: -t, --persistent
> +
> +  Don't exit on the last connection.
> +
> +.. option:: -x, --export-name=NAME
> +
> +  Set the NBD volume export name (default of a zero-length string).
> +
> +.. option:: -D, --description=DESCRIPTION
> +
> +  Set the NBD volume export description, as a human-readable
> +  string.
> +
> +.. option:: -L, --list
> +
> +  Connect as a client and list all details about the exports exposed by
> +  a remote NBD server.  This enables list mode, and is incompatible
> +  with options that change behavior related to a specific export (such as
> +  :option:`--export-name`, :option:`--offset`, ...).
> +
> +.. option:: --tls-creds=ID
> +
> +  Enable mandatory TLS encryption for the server by setting the ID
> +  of the TLS credentials object previously created with the --object
> +  option; or provide the credentials needed for connecting as a client
> +  in list mode.
> +
> +.. option:: --fork
> +
> +  Fork off the server process and exit the parent once the server is running.
> +
> +.. option:: --pid-file=PATH
> +
> +  Store the server's process ID in the given file.
> +
> +.. option:: --tls-authz=ID
> +
> +  Specify the ID of a qauthz object previously created with the
> +  :option:`--object` option. This will be used to authorize connecting users
> +  against their x509 distinguished name.
> +
> +.. option:: -v, --verbose
> +
> +  Display extra debugging information.
> +
> +.. option:: -h, --help
> +
> +  Display this help and exit.
> +
> +.. option:: -V, --version
> +
> +  Display version information and exit.
> +
> +.. option:: -T, --trace [[enable=]PATTERN][,events=FILE][,file=FILE]
> +
> +  .. include:: qemu-option-trace.rst.inc
> +
> +Examples
> +--------
> +
> +Start a server listening on port 10809 that exposes only the
> +guest-visible contents of a qcow2 file, with no TLS encryption, and
> +with the default export name (an empty string). The command is
> +one-shot, and will block until the first successful client
> +disconnects:
> +
> +::
> +
> +  qemu-nbd -f qcow2 file.qcow2
> +
> +Start a long-running server listening with encryption on port 10810,
> +and whitelist clients with a specific X.509 certificate to connect to
> +a 1 megabyte subset of a raw file, using the export name 'subset':
> +
> +::
> +
> +  qemu-nbd \
> +    --object tls-creds-x509,id=tls0,endpoint=server,dir=/path/to/qemutls \
> +    --object 'authz-simple,id=auth0,identity=CN=laptop.example.com,,\
> +              O=Example Org,,L=London,,ST=London,,C=GB' \
> +    --tls-creds tls0 --tls-authz auth0 \
> +    -t -x subset -p 10810 \
> +    --image-opts 
> driver=raw,offset=1M,size=1M,file.driver=file,file.filename=file.raw
> +
> +Serve a read-only copy of just the first MBR partition of a guest
> +image over a Unix socket with as many as 5 simultaneous readers, with
> +a persistent process forked as a daemon:
> +
> +::
> +
> +  qemu-nbd --fork --persistent --shared=5 --socket=/path/to/sock \
> +    --partition=1 --read-only --format=qcow2 file.qcow2
> +
> +Expose the guest-visible contents of a qcow2 file via a block device
> +/dev/nbd0 (and possibly creating /dev/nbd0p1 and friends for
> +partitions found within), then disconnect the device when done.
> +Access to bind qemu-nbd to an /dev/nbd device generally requires root
> +privileges, and may also require the execution of ``modprobe nbd``
> +to enable the kernel NBD client module.  *CAUTION*: Do not use
> +this method to mount filesystems from an untrusted guest image - a
> +malicious guest may have prepared the image to attempt to trigger
> +kernel bugs in partition probing or file system mounting.
> +
> +::
> +
> +  qemu-nbd -c /dev/nbd0 -f qcow2 file.qcow2
> +  qemu-nbd -d /dev/nbd0
> +
> +Query a remote server to see details about what export(s) it is
> +serving on port 10809, and authenticating via PSK:
> +
> +::
> +
> +  qemu-nbd \
> +    --object 
> tls-creds-psk,id=tls0,dir=/tmp/keys,username=eblake,endpoint=client \
> +    --tls-creds tls0 -L -b remote.example.com
> +
> +See also
> +--------
> +
> +:manpage:`qemu(1)`, :manpage:`qemu-img(1)`
> diff --git a/docs/interop/qemu-option-trace.rst.inc 
> b/docs/interop/qemu-option-trace.rst.inc
> new file mode 100644
> index 00000000000..23cfcb48537
> --- /dev/null
> +++ b/docs/interop/qemu-option-trace.rst.inc
> @@ -0,0 +1,30 @@
> +..
> +  The contents of this file must be kept in sync with qemu-option-trace.texi
> +  until all the users of the texi file have been converted to rst and
> +  the texi file can be removed.
> +
> +Specify tracing options.
> +
> +.. option:: [enable=]PATTERN
> +
> +  Immediately enable events matching *PATTERN*
> +  (either event name or a globbing pattern).  This option is only
> +  available if QEMU has been compiled with the ``simple``, ``log``
> +  or ``ftrace`` tracing backend.  To specify multiple events or patterns,
> +  specify the :option:`-trace` option multiple times.
> +
> +  Use :option:`-trace help` to print a list of names of trace points.
> +
> +.. option:: events=FILE
> +
> +  Immediately enable events listed in *FILE*.
> +  The file must contain one event name (as listed in the ``trace-events-all``
> +  file) per line; globbing patterns are accepted too.  This option is only
> +  available if QEMU has been compiled with the ``simple``, ``log`` or
> +  ``ftrace`` tracing backend.
> +
> +.. option:: file=FILE
> +
> +  Log output traces to *FILE*.
> +  This option is only available if QEMU has been compiled with
> +  the ``simple`` tracing backend.
> diff --git a/qemu-doc.texi b/qemu-doc.texi
> index 39f950471f2..617485d1461 100644
> --- a/qemu-doc.texi
> +++ b/qemu-doc.texi
> @@ -633,7 +633,6 @@ encrypted disk images.
>  * disk_images_snapshot_mode:: Snapshot mode
>  * 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
> @@ -724,11 +723,6 @@ state is not saved or restored properly (in particular 
> USB).
>  
>  @include qemu-img.texi
>  
> -@node qemu_nbd_invocation
> -@subsection @code{qemu-nbd} Invocation
> -
> -@include qemu-nbd.texi
> -
>  @include docs/qemu-block-drivers.texi
>  
>  @node pcsys_network
> diff --git a/qemu-nbd.texi b/qemu-nbd.texi
> deleted file mode 100644
> index 7f55657722b..00000000000
> --- a/qemu-nbd.texi
> +++ /dev/null
> @@ -1,214 +0,0 @@
> -@example
> -@c man begin SYNOPSIS
> -@command{qemu-nbd} [OPTION]... @var{filename}
> -
> -@command{qemu-nbd} @option{-L} [OPTION]...
> -
> -@command{qemu-nbd} @option{-d} @var{dev}
> -@c man end
> -@end example
> -
> -@c man begin DESCRIPTION
> -
> -Export a QEMU disk image using the NBD protocol.
> -
> -Other uses:
> -@itemize
> -@item
> -Bind a /dev/nbdX block device to a QEMU server (on Linux).
> -@item
> -As a client to query exports of a remote NBD server.
> -@end itemize
> -
> -@c man end
> -
> -@c man begin OPTIONS
> -@var{filename} is a disk image filename, or a set of block
> -driver options if @option{--image-opts} is specified.
> -
> -@var{dev} is an NBD device.
> -
> -@table @option
> -@item --object type,id=@var{id},...props...
> -Define a new instance of the @var{type} object class identified by @var{id}.
> -See the @code{qemu(1)} manual page for full details of the properties
> -supported. The common object types that it makes sense to define are the
> -@code{secret} object, which is used to supply passwords and/or encryption
> -keys, and the @code{tls-creds} object, which is used to supply TLS
> -credentials for the qemu-nbd server or client.
> -@item -p, --port=@var{port}
> -The TCP port to listen on as a server, or connect to as a client
> -(default @samp{10809}).
> -@item -o, --offset=@var{offset}
> -The offset into the image.
> -@item -b, --bind=@var{iface}
> -The interface to bind to as a server, or connect to as a client
> -(default @samp{0.0.0.0}).
> -@item -k, --socket=@var{path}
> -Use a unix socket with path @var{path}.
> -@item --image-opts
> -Treat @var{filename} as a set of image options, instead of a plain
> -filename. If this flag is specified, the @var{-f} flag should
> -not be used, instead the '@code{format=}' option should be set.
> -@item -f, --format=@var{fmt}
> -Force the use of the block driver for format @var{fmt} instead of
> -auto-detecting.
> -@item -r, --read-only
> -Export the disk as read-only.
> -@item -P, --partition=@var{num}
> -Deprecated: Only expose MBR partition @var{num}.  Understands physical
> -partitions 1-4 and logical partition 5. New code should instead use
> -@option{--image-opts} with the raw driver wrapping a subset of the
> -original image.
> -@item -B, --bitmap=@var{name}
> -If @var{filename} has a qcow2 persistent bitmap @var{name}, expose
> -that bitmap via the ``qemu:dirty-bitmap:@var{name}'' context
> -accessible through NBD_OPT_SET_META_CONTEXT.
> -@item -s, --snapshot
> -Use @var{filename} as an external snapshot, create a temporary
> -file with backing_file=@var{filename}, redirect the write to
> -the temporary one.
> -@item -l, --load-snapshot=@var{snapshot_param}
> -Load an internal snapshot inside @var{filename} and export it
> -as an read-only device, @var{snapshot_param} format is
> -'snapshot.id=[ID],snapshot.name=[NAME]' or '[ID_OR_NAME]'
> -@item -n, --nocache
> -@itemx --cache=@var{cache}
> -The cache mode to be used with the file.  See the documentation of
> -the emulator's @code{-drive cache=...} option for allowed values.
> -@item --aio=@var{aio}
> -Set the asynchronous I/O mode between @samp{threads} (the default)
> -and @samp{native} (Linux only).
> -@item --discard=@var{discard}
> -Control whether @dfn{discard} (also known as @dfn{trim} or @dfn{unmap})
> -requests are ignored or passed to the filesystem.  @var{discard} is one of
> -@samp{ignore} (or @samp{off}), @samp{unmap} (or @samp{on}).  The default is
> -@samp{ignore}.
> -@item --detect-zeroes=@var{detect-zeroes}
> -Control the automatic conversion of plain zero writes by the OS to
> -driver-specific optimized zero write commands.  @var{detect-zeroes} is one of
> -@samp{off}, @samp{on} or @samp{unmap}.  @samp{unmap}
> -converts a zero write to an unmap operation and can only be used if
> -@var{discard} is set to @samp{unmap}.  The default is @samp{off}.
> -@item -c, --connect=@var{dev}
> -Connect @var{filename} to NBD device @var{dev} (Linux only).
> -@item -d, --disconnect
> -Disconnect the device @var{dev} (Linux only).
> -@item -e, --shared=@var{num}
> -Allow up to @var{num} clients to share the device (default
> -@samp{1}). Safe for readers, but for now, consistency is not
> -guaranteed between multiple writers.
> -@item -t, --persistent
> -Don't exit on the last connection.
> -@item -x, --export-name=@var{name}
> -Set the NBD volume export name (default of a zero-length string).
> -@item -D, --description=@var{description}
> -Set the NBD volume export description, as a human-readable
> -string.
> -@item -L, --list
> -Connect as a client and list all details about the exports exposed by
> -a remote NBD server.  This enables list mode, and is incompatible
> -with options that change behavior related to a specific export (such as
> -@option{--export-name}, @option{--offset}, ...).
> -@item --tls-creds=ID
> -Enable mandatory TLS encryption for the server by setting the ID
> -of the TLS credentials object previously created with the --object
> -option; or provide the credentials needed for connecting as a client
> -in list mode.
> -@item --fork
> -Fork off the server process and exit the parent once the server is running.
> -@item --pid-file=PATH
> -Store the server's process ID in the given file.
> -@item --tls-authz=ID
> -Specify the ID of a qauthz object previously created with the
> ---object option. This will be used to authorize connecting users
> -against their x509 distinguished name.
> -@item -v, --verbose
> -Display extra debugging information.
> -@item -h, --help
> -Display this help and exit.
> -@item -V, --version
> -Display version information and exit.
> -@item -T, --trace 
> [[enable=]@var{pattern}][,events=@var{file}][,file=@var{file}]
> -@findex --trace
> -@include qemu-option-trace.texi
> -@end table
> -
> -@c man end
> -
> -@c man begin EXAMPLES
> -Start a server listening on port 10809 that exposes only the
> -guest-visible contents of a qcow2 file, with no TLS encryption, and
> -with the default export name (an empty string). The command is
> -one-shot, and will block until the first successful client
> -disconnects:
> -
> -@example
> -qemu-nbd -f qcow2 file.qcow2
> -@end example
> -
> -Start a long-running server listening with encryption on port 10810,
> -and whitelist clients with a specific X.509 certificate to connect to
> -a 1 megabyte subset of a raw file, using the export name 'subset':
> -
> -@example
> -qemu-nbd \
> -  --object tls-creds-x509,id=tls0,endpoint=server,dir=/path/to/qemutls \
> -  --object 'authz-simple,id=auth0,identity=CN=laptop.example.com,,\
> -            O=Example Org,,L=London,,ST=London,,C=GB' \
> -  --tls-creds tls0 --tls-authz auth0 \
> -  -t -x subset -p 10810 \
> -  --image-opts 
> driver=raw,offset=1M,size=1M,file.driver=file,file.filename=file.raw
> -@end example
> -
> -Serve a read-only copy of just the first MBR partition of a guest
> -image over a Unix socket with as many as 5 simultaneous readers, with
> -a persistent process forked as a daemon:
> -
> -@example
> -qemu-nbd --fork --persistent --shared=5 --socket=/path/to/sock \
> -  --partition=1 --read-only --format=qcow2 file.qcow2
> -@end example
> -
> -Expose the guest-visible contents of a qcow2 file via a block device
> -/dev/nbd0 (and possibly creating /dev/nbd0p1 and friends for
> -partitions found within), then disconnect the device when done.
> -Access to bind qemu-nbd to an /dev/nbd device generally requires root
> -privileges, and may also require the execution of @code{modprobe nbd}
> -to enable the kernel NBD client module.  @emph{CAUTION}: Do not use
> -this method to mount filesystems from an untrusted guest image - a
> -malicious guest may have prepared the image to attempt to trigger
> -kernel bugs in partition probing or file system mounting.
> -
> -@example
> -qemu-nbd -c /dev/nbd0 -f qcow2 file.qcow2
> -qemu-nbd -d /dev/nbd0
> -@end example
> -
> -Query a remote server to see details about what export(s) it is
> -serving on port 10809, and authenticating via PSK:
> -
> -@example
> -qemu-nbd \
> -  --object 
> tls-creds-psk,id=tls0,dir=/tmp/keys,username=eblake,endpoint=client \
> -  --tls-creds tls0 -L -b remote.example.com
> -@end example
> -
> -@c man end
> -
> -@ignore
> -
> -@setfilename qemu-nbd
> -@settitle QEMU Disk Network Block Device Server
> -
> -@c man begin AUTHOR
> -Copyright (C) 2006 Anthony Liguori <address@hidden>.
> -This is free software; see the source for copying conditions.  There is NO
> -warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
> -@c man end
> -
> -@c man begin SEEALSO
> -qemu(1), qemu-img(1)
> -@c man end
> -
> -@end ignore
> diff --git a/qemu-option-trace.texi b/qemu-option-trace.texi
> index 7d1b7f05c54..162f1528d21 100644
> --- a/qemu-option-trace.texi
> +++ b/qemu-option-trace.texi
> @@ -1,3 +1,7 @@
> +@c The contents of this file must be kept in sync with 
> qemu-option-trace.rst.inc
> +@c until all the users of the texi file have been converted to rst and
> +@c the texi file can be removed.
> +
>  Specify tracing options.
>  
>  @table @option


-- 
Alex Bennée