From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:47681) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cba6G-0000Sn-S6 for qemu-devel@nongnu.org; Wed, 08 Feb 2017 16:48:33 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cba6C-0003r8-0l for qemu-devel@nongnu.org; Wed, 08 Feb 2017 16:48:28 -0500 Received: from mail-qk0-x243.google.com ([2607:f8b0:400d:c09::243]:36341) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1cba6B-0003qy-Sk for qemu-devel@nongnu.org; Wed, 08 Feb 2017 16:48:23 -0500 Received: by mail-qk0-x243.google.com with SMTP id i34so19724603qkh.3 for ; Wed, 08 Feb 2017 13:48:23 -0800 (PST) Sender: =?UTF-8?Q?Philippe_Mathieu=2DDaud=C3=A9?= References: <1486564125-31366-1-git-send-email-ashijeetacharya@gmail.com> From: =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= Message-ID: Date: Wed, 8 Feb 2017 18:48:19 -0300 MIME-Version: 1.0 In-Reply-To: <1486564125-31366-1-git-send-email-ashijeetacharya@gmail.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 8bit 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: qemu-devel@nongnu.org Cc: Ashijeet Acharya , thuth@redhat.com, quintela@redhat.com, groug@kaod.org, pbonzini@redhat.com, dgilbert@redhat.com On 02/08/2017 11:28 AM, Ashijeet Acharya 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: Philippe Mathieu-Daudé > --- > 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); > + } > } > > /* >