It was found that 'qemu-nbd' is not able to work with some disk images
exported from Azure. Looking at the 512b footer (which contains VPC
metadata):
00000000 63 6f 6e 65 63 74 69 78 00 00 00 02 00 01 00 00 |conectix........|
00000010 ff ff ff ff ff ff ff ff 2e c7 9b 96 77 61 00 00 |............wa..|
00000020 00 07 00 00 57 69 32 6b 00 00 00 01 40 00 00 00 |....Wi2k....@...|
00000030 00 00 00 01 40 00 00 00 28 a2 10 3f 00 00 00 02 |....@...(..?....|
00000040 ff ff e7 47 8c 54 df 94 bd 35 71 4c 94 5f e5 44 |...G.T...5qL._.D|
00000050 44 53 92 1a 00 00 00 00 00 00 00 00 00 00 00 00 |DS..............|
00000060 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
we can see that Azure uses a different 'Creator application' --
'wa\0\0' (offset 0x1c, likely reads as 'Windows Azure') and QEMU uses this
field to determine how it can get image size. Apparently, Azure uses 'new'
method, just like Hyper-V.
Signed-off-by: Vitaly Kuznetsov <vkuzn...@redhat.com>
---
Alternatively, we can probably make 'current_size' the default and only use
CHS for 'vpc '/'qemu'.
---
block/vpc.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/block/vpc.c b/block/vpc.c
index d95a204612b7..b67798697c15 100644
--- a/block/vpc.c
+++ b/block/vpc.c
@@ -321,6 +321,7 @@ static int vpc_open(BlockDriverState *bs, QDict *options,
int flags,
* 'qemu' : CHS QEMU (uses disk geometry)
* 'qem2' : current_size QEMU (uses current_size)
* 'win ' : current_size Hyper-V
+ * 'wa\0\0': current_size Azure
* 'd2v ' : current_size Disk2vhd
* 'tap\0' : current_size XenServer
* 'CTXS' : current_size XenConverter
@@ -330,6 +331,7 @@ static int vpc_open(BlockDriverState *bs, QDict *options,
int flags,
* that have CHS geometry of the maximum size.
*/
use_chs = (!!strncmp(footer->creator_app, "win ", 4) &&
+ !!memcmp(footer->creator_app, "wa\0", 4) &&
!!strncmp(footer->creator_app, "qem2", 4) &&
!!strncmp(footer->creator_app, "d2v ", 4) &&
!!strncmp(footer->creator_app, "CTXS", 4) &&
--
2.47.0
