Re: [PATCH v3 16/16] tests/qtest/migration: Add a test for mapped-ram with passing of fds

[Peter Xu <peterx@redhat.com>]

On Mon, Jun 17, 2024 at 03:57:31PM -0300, Fabiano Rosas wrote:
> Add a multifd test for mapped-ram with passing of fds into QEMU. This
> is how libvirt will consume the feature.
> 
> There are a couple of details to the fdset mechanism:
> 
> - multifd needs two distinct file descriptors (not duplicated with
>   dup()) so it can enable O_DIRECT only on the channels that do
>   aligned IO. The dup() system call creates file descriptors that
>   share status flags, of which O_DIRECT is one.
> 
> - the open() access mode flags used for the fds passed into QEMU need
>   to match the flags QEMU uses to open the file. Currently O_WRONLY
>   for src and O_RDONLY for dst.
> 
> Note that fdset code goes under _WIN32 because fd passing is not
> supported on Windows.
> 
> Signed-off-by: Fabiano Rosas <farosas@suse.de>
> ---
> - dropped Peter's r-b
> 
> - stopped removing the fdset at the end of the tests. The migration
> code should always cleanup after itself.

Ah, that looks also ok.

Reviewed-by: Peter Xu <peterx@redhat.com>

-- 
Peter Xu