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shm_open() creates and opens a new POSIX shared memory object. A POSIX shared memory object allows creating memory backend with an associated file descriptor that can be shared with external processes (e.g. vhost-user). The new `memory-backend-shm` can be used as an alternative when `memory-backend-memfd` is not available (Linux only), since shm_open() should be provided by any POSIX-compliant operating system. This backend mimics memfd, allocating memory that is practically anonymous. In theory shm_open() requires a name, but this is allocated for a short time interval and shm_unlink() is called right after shm_open(). After that, only fd is shared with external processes (e.g., vhost-user) as if it were associated with anonymous memory. In the future we may also allow the user to specify the name to be passed to shm_open(), but for now we keep the backend simple, mimicking anonymous memory such as memfd. Acked-by:
David Hildenbrand <david@redhat.com> Acked-by:
Stefan Hajnoczi <stefanha@redhat.com> Acked-by: Markus Armbruster <armbru@redhat.com> (QAPI schema) Signed-off-by:
Stefano Garzarella <sgarzare@redhat.com> Message-Id: <20240618100519.145853-1-sgarzare@redhat.com> Reviewed-by:
Michael S. Tsirkin <mst@redhat.com> Signed-off-by:
Michael S. Tsirkin <mst@redhat.com>
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