tree 7a1339ea43682f9651bbd63c51d5ff3f140cc7cb
parent 9db191251381c75e57201f7b07330ca982a55d1e
author Fabiano Rosas <farosas@suse.de> 1709220608 -0300
committer Peter Xu <peterx@redhat.com> 1709278924 +0800

migration/multifd: Allow multifd without packets

For the upcoming support to the new 'mapped-ram' migration stream
format, we cannot use multifd packets because each write into the
ramblock section in the migration file is expected to contain only the
guest pages. They are written at their respective offsets relative to
the ramblock section header.

There is no space for the packet information and the expected gains
from the new approach come partly from being able to write the pages
sequentially without extraneous data in between.

The new format also simply doesn't need the packets and all necessary
information can be taken from the standard migration headers with some
(future) changes to multifd code.

Use the presence of the mapped-ram capability to decide whether to
send packets.

This only moves code under multifd_use_packets(), it has no effect for
now as mapped-ram cannot yet be enabled with multifd.

Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20240229153017.2221-15-farosas@suse.de
Signed-off-by: Peter Xu <peterx@redhat.com>