qemu-e2k/docs/system/images.rst

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docs/system: convert Texinfo documentation to rST Apart from targets.rst, which was written by hand, this is an automated conversion obtained with the following command: makeinfo --force -o - --docbook \ -D 'qemu_system_x86 QEMU_SYSTEM_X86_MACRO' \ -D 'qemu_system QEMU_SYSTEM_MACRO' \ $texi | pandoc -f docbook -t rst+smart | perl -e ' $/=undef; $_ = <>; s/^- − /- /gm; s/QEMU_SYSTEM_MACRO/|qemu_system|/g; s/QEMU_SYSTEM_X86_MACRO/|qemu_system_x86|/g; s/(?=::\n\n +\|qemu)/.. parsed-literal/g; s/:\n\n::$/::/gm; print' > $rst In addition, the following changes were made manually: - target-i386.rst and target-mips.rst: replace CPU model documentation with an include directive - monitor.rst: replace the command section with a comment - images.rst: add toctree - target-arm.rst: Replace use of :math: (which Sphinx complains about) with :sup:, and hide it behind |I2C| and |I2C| substitutions. Content that is not @included remains exclusive to qemu-doc.texi. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Peter Maydell <peter.maydell@linaro.org> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Tested-by: Alex Bennée <alex.bennee@linaro.org> Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Message-id: 20200228153619.9906-20-peter.maydell@linaro.org Message-id: 20200226113034.6741-19-pbonzini@redhat.com [PMM: Fixed target-arm.rst use of :math:; remove out of date note about images.rst from commit message; fixed expansion of |qemu_system_x86|; use parsed-literal in invocation.rst when we want to use |qemu_system_x86|; fix incorrect subsection level for "OS requirements" in target-i386.rst; fix incorrect syntax for making links to other sections of the manual] Reviewed-by: Peter Maydell <peter.maydell@linaro.org> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2020-02-28 16:36:05 +01:00
.. _disk_005fimages:
Disk Images
-----------
QEMU supports many disk image formats, including growable disk images
(their size increase as non empty sectors are written), compressed and
encrypted disk images.
.. _disk_005fimages_005fquickstart:
Quick start for disk image creation
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
You can create a disk image with the command::
qemu-img create myimage.img mysize
where myimage.img is the disk image filename and mysize is its size in
kilobytes. You can add an ``M`` suffix to give the size in megabytes and
a ``G`` suffix for gigabytes.
See the qemu-img invocation documentation for more information.
.. _disk_005fimages_005fsnapshot_005fmode:
Snapshot mode
~~~~~~~~~~~~~
If you use the option ``-snapshot``, all disk images are considered as
read only. When sectors in written, they are written in a temporary file
created in ``/tmp``. You can however force the write back to the raw
disk images by using the ``commit`` monitor command (or C-a s in the
serial console).
.. _vm_005fsnapshots:
VM snapshots
~~~~~~~~~~~~
VM snapshots are snapshots of the complete virtual machine including CPU
state, RAM, device state and the content of all the writable disks. In
order to use VM snapshots, you must have at least one non removable and
writable block device using the ``qcow2`` disk image format. Normally
this device is the first virtual hard drive.
Use the monitor command ``savevm`` to create a new VM snapshot or
replace an existing one. A human readable name can be assigned to each
snapshot in addition to its numerical ID.
Use ``loadvm`` to restore a VM snapshot and ``delvm`` to remove a VM
snapshot. ``info snapshots`` lists the available snapshots with their
associated information::
(qemu) info snapshots
Snapshot devices: hda
Snapshot list (from hda):
ID TAG VM SIZE DATE VM CLOCK
1 start 41M 2006-08-06 12:38:02 00:00:14.954
2 40M 2006-08-06 12:43:29 00:00:18.633
3 msys 40M 2006-08-06 12:44:04 00:00:23.514
A VM snapshot is made of a VM state info (its size is shown in
``info snapshots``) and a snapshot of every writable disk image. The VM
state info is stored in the first ``qcow2`` non removable and writable
block device. The disk image snapshots are stored in every disk image.
The size of a snapshot in a disk image is difficult to evaluate and is
not shown by ``info snapshots`` because the associated disk sectors are
shared among all the snapshots to save disk space (otherwise each
snapshot would need a full copy of all the disk images).
When using the (unrelated) ``-snapshot`` option
(:ref:`disk_005fimages_005fsnapshot_005fmode`),
you can always make VM snapshots, but they are deleted as soon as you
exit QEMU.
VM snapshots currently have the following known limitations:
- They cannot cope with removable devices if they are removed or
inserted after a snapshot is done.
- A few device drivers still have incomplete snapshot support so their
state is not saved or restored properly (in particular USB).
.. include:: qemu-block-drivers.rst.inc