[Qemu-devel] [PATCH 12/16] block: Fix vpc initialization of the Dynamic Disk Header

[Kevin Wolf <kwolf@redhat.com>]

From: Charles Arnold <carnold@suse.com>

The Data Offset field in the Dynamic Disk Header is an 8 byte field.
Although the specification (2006-10-11) gives an example of initializing
only the first 4 bytes, images generated by Microsoft on Windows initialize
all 8 bytes.

Failure to initialize all 8 bytes results in errors from utilities
like Citrix's vhd-util which checks specifically for the proper Data
Offset field initialization.

Signed-off-by: Charles Arnold <carnold@suse.com>
Reviewed-by: Andreas Färber <afaerber@suse.de>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/vpc.c |    6 +++++-
 1 files changed, 5 insertions(+), 1 deletions(-)

diff --git a/block/vpc.c b/block/vpc.c
index 79be7d0..54633b6 100644
--- a/block/vpc.c
+++ b/block/vpc.c
@@ -617,7 +617,11 @@ static int vpc_create(const char *filename, QEMUOptionParameter *options)
 
     memcpy(dyndisk_header->magic, "cxsparse", 8);
 
-    dyndisk_header->data_offset = be64_to_cpu(0xFFFFFFFF);
+    /*
+     * Note: The spec is actually wrong here for data_offset, it says
+     * 0xFFFFFFFF, but MS tools expect all 64 bits to be set.
+     */
+    dyndisk_header->data_offset = be64_to_cpu(0xFFFFFFFFFFFFFFFFULL);
     dyndisk_header->table_offset = be64_to_cpu(3 * 512);
     dyndisk_header->version = be32_to_cpu(0x00010000);
     dyndisk_header->block_size = be32_to_cpu(block_size);
-- 
1.7.6.4