Re: [Qemu-devel] [PATCH v4 2/3] Add memfd based hostmem

[Eduardo Habkost <ehabkost@redhat.com>]

On Wed, Jun 21, 2017 at 04:02:18PM +0200, Marc-André Lureau wrote:
> Add a new memory backend, similar to hostmem-file, except that it
> doesn't need to create files. It also enforces memory sealing.
> 
> This backend is mainly useful for sharing the memory with other
> processes.

How exactly can the memfd be used to share memory?  Is there an existing
mechanism for sharing the memfd file descriptor with another process?


> 
> Note that Linux supports transparent huge-pages of shmem/memfd memory
> since 4.8. It is relatively easier to set up THP than a dedicate
> hugepage mount point by using "madvise" in
> /sys/kernel/mm/transparent_hugepage/shmem_enabled.
> 
> Usage:
> -object memory-backend-memfd,id=mem1,size=1G
> 
> Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
> ---
>  backends/hostmem-memfd.c | 67 ++++++++++++++++++++++++++++++++++++++++++++++++
>  backends/Makefile.objs   |  2 ++
>  qemu-options.hx          | 11 ++++++++
>  3 files changed, 80 insertions(+)
>  create mode 100644 backends/hostmem-memfd.c
> 
[...]

-- 
Eduardo