system/devices/ivshmem.rst

1 Inter-VM Shared Memory device
2 -----------------------------
4 On Linux hosts, a shared memory device is available. The basic syntax
7 .. parsed-literal::
9    |qemu_system_x86| -device ivshmem-plain,memdev=hostmem
11 where hostmem names a host memory backend. For a POSIX shared memory
16    -object memory-backend-file,size=1M,share,mem-path=/dev/shm/ivshmem,id=hostmem
19 shared memory region. Interrupt support requires using a shared memory
21 shared memory server is qemu.git/contrib/ivshmem-server. An example
22 syntax when using the shared memory server is:
24 .. parsed-literal::
27    ivshmem-server -p pidfile -S path -m shm-name -l shm-size -n vectors
30    |qemu_system_x86| -device ivshmem-doorbell,vectors=vectors,chardev=id
31                     -chardev socket,path=path,id=id
36 :doc:`../../specs/ivshmem-spec`).
41 With device property ``master=on``, the guest will copy the shared
42 memory on migration to the destination host. With ``master=off``, the
47 At most one of the devices sharing the same memory can be master. The
54 memory backend that has hugepage support:
56 .. parsed-literal::
58 …|qemu_system_x86| -object memory-backend-file,size=1G,mem-path=/dev/hugepages/my-shmem-file,share,…
59                     -device ivshmem-plain,memdev=mb1
61 ivshmem-server also supports hugepages mount points with the ``-m``
62 memory path argument.