On 17/07/2015 12:34, Marc-André Lureau wrote: > On Fri, Jul 17, 2015 at 4:25 AM, Paolo Bonzini <pbonz...@redhat.com> wrote: > > But LOG_BASE makes little sense across processes, and LOG_FD is unused > > in QEMU, isn't it? So this patch is not enough to add support of live > > migration. > > You are right, LOG_BASE doesn't make much sense, and LOG_FD isn't > used, despite some code already there. Furthermore, the log is > allocated with regular malloc, hardly shareable.
LOG_FD is implemented in the kernel drivers/vhost/vhost.c. It seems to be an eventfd-like mechanism to save on dirty bitmap scans. However, it's not well documented how to implement it in a correct way. In any case, live migration needs a new message type (like LOG_MMAP_FD) in the vhost-user protocol. Paolo
