Hi
----- Original Message -----
> On Tue, Sep 29, 2015 at 06:34:36PM +0200, [email protected] wrote:
> > From: Marc-André Lureau <[email protected]>
> >
> > Add an open/unlink/mmap fallback for system that do not support memfd.
> > This patch may require additional SELinux policies to work for enforced
> > systems, but should gracefully fail nonetheless.
> >
> > Signed-off-by: Marc-André Lureau <[email protected]>
>
> I'd rather just fail migration.
So we don't provide this compatibility code and migration should fail.
Would it be enough to check if memfd works at early runtime and add a migration
blocker for vhost-user? Or is it possible to recover if migration fails when
memfd fails to allocate? I would thing the former is better.
>
> > ---
> > util/memfd.c | 22 ++++++++++++++++++++--
> > 1 file changed, 20 insertions(+), 2 deletions(-)
> >
> > diff --git a/util/memfd.c b/util/memfd.c
> > index 3168902..970b5b0 100644
> > --- a/util/memfd.c
> > +++ b/util/memfd.c
> > @@ -84,8 +84,26 @@ void *qemu_memfd_alloc(const char *name, size_t size,
> > unsigned int seals,
> > return NULL;
> > }
> > } else {
> > - perror("memfd");
> > - return NULL;
> > + const char *tmpdir = getenv("TMPDIR");
> > + gchar *fname;
> > +
> > + tmpdir = tmpdir ? tmpdir : "/tmp";
> > +
> > + fname = g_strdup_printf("%s/memfd-XXXXXX", tmpdir);
> > + mfd = mkstemp(fname);
> > + unlink(fname);
> > + g_free(fname);
> > +
> > + if (mfd == -1) {
> > + perror("mkstemp");
> > + return NULL;
> > + }
> > +
> > + if (ftruncate(mfd, size) == -1) {
> > + perror("ftruncate");
> > + close(mfd);
> > + return NULL;
> > + }
> > }
> >
> > ptr = mmap(0, size, PROT_READ | PROT_WRITE, MAP_SHARED, mfd, 0);
> > --
> > 2.4.3
>
