Make state snapshots compatible with SD cards.

This patch introduces a check such that only drives exporting a
snapshot creation function are considered for storing snapshots.
SD cards are mounted with a raw file system, which does not
support snapshots. Since the SD card is now skipped, the actual
snapshot image can be safely mounted on hdb rather than hda.

The contents of the SD card itself are included in the snapshot
however, since they are accessed with the NAND driver (which
saves the contents of the underlying files).

Change-Id: I4816b6e54e227aca356389c15ce9f5c1282d2464

1 files changed, 9 insertions, 0 deletions

diff --git a/block.c b/block.c
index 6d05a58..852cb3e 100644
--- a/block.c
+++ b/block.c
@@ -1181,6 +1181,15 @@ int bdrv_get_buffer(BlockDriverState *bs, uint8_t *buf, int64_t pos, int size)
 /**************************************************************/
 /* handling of snapshots */
 
+int bdrv_can_snapshot(BlockDriverState *bs)
+{
+    return ( bs &&
+             !bdrv_is_removable(bs) &&
+             !bdrv_is_read_only(bs) &&
+             bs->drv &&
+             bs->drv->bdrv_snapshot_create );
+}
+
 int bdrv_snapshot_create(BlockDriverState *bs,
                          QEMUSnapshotInfo *sn_info)
 {