From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:53360) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cbTEo-0006Wd-2n for qemu-devel@nongnu.org; Wed, 08 Feb 2017 09:28:51 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cbTEk-00066Z-3Q for qemu-devel@nongnu.org; Wed, 08 Feb 2017 09:28:50 -0500 Received: from mail-pg0-x244.google.com ([2607:f8b0:400e:c05::244]:36759) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1cbTEj-00066M-S6 for qemu-devel@nongnu.org; Wed, 08 Feb 2017 09:28:46 -0500 Received: by mail-pg0-x244.google.com with SMTP id 75so15335124pgf.3 for ; Wed, 08 Feb 2017 06:28:45 -0800 (PST) From: Ashijeet Acharya Date: Wed, 8 Feb 2017 19:58:45 +0530 Message-Id: <1486564125-31366-1-git-send-email-ashijeetacharya@gmail.com> Subject: [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: thuth@redhat.com Cc: quintela@redhat.com, dgilbert@redhat.com, berrange@redhat.com, pbonzini@redhat.com, groug@kaod.org, qemu-devel@nongnu.org, Ashijeet Acharya 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 --- 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