From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:50427) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cbUfW-0003HX-VT for qemu-devel@nongnu.org; Wed, 08 Feb 2017 11:00:34 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cbUfT-0003x7-Sf for qemu-devel@nongnu.org; Wed, 08 Feb 2017 11:00:31 -0500 Received: from mx1.redhat.com ([209.132.183.28]:37152) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1cbUfT-0003wj-O3 for qemu-devel@nongnu.org; Wed, 08 Feb 2017 11:00:27 -0500 Date: Wed, 8 Feb 2017 16:00:22 +0000 From: "Dr. David Alan Gilbert" Message-ID: <20170208160021.GM2341@work-vm> References: <1486564125-31366-1-git-send-email-ashijeetacharya@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1486564125-31366-1-git-send-email-ashijeetacharya@gmail.com> Subject: Re: [Qemu-devel] [PATCH v3] migrate: Introduce zero RAM checks to skip RAM migration List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Ashijeet Acharya Cc: thuth@redhat.com, quintela@redhat.com, berrange@redhat.com, pbonzini@redhat.com, groug@kaod.org, qemu-devel@nongnu.org * Ashijeet Acharya (ashijeetacharya@gmail.com) wrote: > Migration of a "none" machine with no RAM crashes abruptly as > bitmap_new() fails and thus aborts. Instead place zero RAM checks at > appropriate places to skip migration of RAM in this case and complete > migration successfully for devices only. > > Signed-off-by: Ashijeet Acharya Reviewed-by: Dr. David Alan Gilbert > --- > Changes in v3: > - handle migration cleanup appropriately (Dave) > Changes in v2: > - try to migrate successfully by skipping RAM (Paolo, Greg) > - drop the idea of erroring out and failing nicely > --- > migration/ram.c | 22 +++++++++++++++------- > 1 file changed, 15 insertions(+), 7 deletions(-) > > diff --git a/migration/ram.c b/migration/ram.c > index ef8fadf..faff5ab 100644 > --- a/migration/ram.c > +++ b/migration/ram.c > @@ -1325,6 +1325,11 @@ static int ram_find_and_save_block(QEMUFile *f, bool last_stage, > ram_addr_t dirty_ram_abs; /* Address of the start of the dirty page in > ram_addr_t space */ > > + /* No dirty page as there is zero RAM */ > + if (!ram_bytes_total()) { > + return pages; > + } > + > pss.block = last_seen_block; > pss.offset = last_offset; > pss.complete_round = false; > @@ -1912,14 +1917,17 @@ static int ram_save_init_globals(void) > bytes_transferred = 0; > reset_ram_globals(); > > - ram_bitmap_pages = last_ram_offset() >> TARGET_PAGE_BITS; > migration_bitmap_rcu = g_new0(struct BitmapRcu, 1); > - migration_bitmap_rcu->bmap = bitmap_new(ram_bitmap_pages); > - bitmap_set(migration_bitmap_rcu->bmap, 0, ram_bitmap_pages); > - > - if (migrate_postcopy_ram()) { > - migration_bitmap_rcu->unsentmap = bitmap_new(ram_bitmap_pages); > - bitmap_set(migration_bitmap_rcu->unsentmap, 0, ram_bitmap_pages); > + /* Skip setting bitmap if there is no RAM */ > + if (ram_bytes_total()) { > + ram_bitmap_pages = last_ram_offset() >> TARGET_PAGE_BITS; > + migration_bitmap_rcu->bmap = bitmap_new(ram_bitmap_pages); > + bitmap_set(migration_bitmap_rcu->bmap, 0, ram_bitmap_pages); > + > + if (migrate_postcopy_ram()) { > + migration_bitmap_rcu->unsentmap = bitmap_new(ram_bitmap_pages); > + bitmap_set(migration_bitmap_rcu->unsentmap, 0, ram_bitmap_pages); > + } > } > > /* > -- > 2.6.2 > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK