[SeaBIOS] [PATCHv2] add write support to virtio-blk

[Kevin O'Connor]

On Wed, Aug 18, 2010 at 05:46:20PM +0300, Gleb Natapov wrote:
> Windows XP does write to sector 0 during installation and prints
> mysterious error if write fails. Interestingly if write drops data,
> but returns OK to Windows installer installation proceed without
> complains and completes successfully.
[...]
> +    case CMD_FORMAT:
>          return DISK_RET_EWRITEPROTECT;

If CMD_WRITE is implemented, I think CMD_FORMAT should just return
DISK_RET_SUCCESS (as ata does).

Otherwise, looks okay to me.

-Kevin