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-rw-r--r--qemu-options.hx16
1 files changed, 16 insertions, 0 deletions
diff --git a/qemu-options.hx b/qemu-options.hx
index 8ca7f34ef0..ad6521ef5e 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -5240,6 +5240,22 @@ SRST
 
         The ``share`` boolean option is on by default with memfd.
 
+    ``-object memory-backend-shm,id=id,merge=on|off,dump=on|off,share=on|off,prealloc=on|off,size=size,host-nodes=host-nodes,policy=default|preferred|bind|interleave``
+        Creates a POSIX shared memory backend object, which allows
+        QEMU to share the memory with an external process (e.g. when
+        using vhost-user).
+
+        ``memory-backend-shm`` is a more portable and less featureful version
+        of ``memory-backend-memfd``. It can then be used in any POSIX system,
+        especially when memfd is not supported.
+
+        Please refer to ``memory-backend-file`` for a description of the
+        options.
+
+        The ``share`` boolean option is on by default with shm. Setting it to
+        off will cause a failure during allocation because it is not supported
+        by this backend.
+
     ``-object iommufd,id=id[,fd=fd]``
         Creates an iommufd backend which allows control of DMA mapping
         through the ``/dev/iommu`` device.