mirror of
https://github.com/qemu/qemu.git
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324b2298fe
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[PMM: Fixed target-arm.rst use of :math:; remove out of date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>
65 lines
2.2 KiB
ReStructuredText
65 lines
2.2 KiB
ReStructuredText
.. _pcsys_005fivshmem:
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Inter-VM Shared Memory device
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-----------------------------
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On Linux hosts, a shared memory device is available. The basic syntax
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is:
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.. parsed-literal::
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|qemu_system_x86| -device ivshmem-plain,memdev=hostmem
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where hostmem names a host memory backend. For a POSIX shared memory
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backend, use something like
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::
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-object memory-backend-file,size=1M,share,mem-path=/dev/shm/ivshmem,id=hostmem
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If desired, interrupts can be sent between guest VMs accessing the same
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shared memory region. Interrupt support requires using a shared memory
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server and using a chardev socket to connect to it. The code for the
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shared memory server is qemu.git/contrib/ivshmem-server. An example
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syntax when using the shared memory server is:
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.. parsed-literal::
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# First start the ivshmem server once and for all
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ivshmem-server -p pidfile -S path -m shm-name -l shm-size -n vectors
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# Then start your qemu instances with matching arguments
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|qemu_system_x86| -device ivshmem-doorbell,vectors=vectors,chardev=id
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-chardev socket,path=path,id=id
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When using the server, the guest will be assigned a VM ID (>=0) that
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allows guests using the same server to communicate via interrupts.
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Guests can read their VM ID from a device register (see
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ivshmem-spec.txt).
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Migration with ivshmem
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~~~~~~~~~~~~~~~~~~~~~~
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With device property ``master=on``, the guest will copy the shared
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memory on migration to the destination host. With ``master=off``, the
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guest will not be able to migrate with the device attached. In the
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latter case, the device should be detached and then reattached after
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migration using the PCI hotplug support.
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At most one of the devices sharing the same memory can be master. The
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master must complete migration before you plug back the other devices.
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ivshmem and hugepages
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~~~~~~~~~~~~~~~~~~~~~
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Instead of specifying the <shm size> using POSIX shm, you may specify a
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memory backend that has hugepage support:
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.. parsed-literal::
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|qemu_system_x86| -object memory-backend-file,size=1G,mem-path=/dev/hugepages/my-shmem-file,share,id=mb1
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-device ivshmem-plain,memdev=mb1
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ivshmem-server also supports hugepages mount points with the ``-m``
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memory path argument.
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