On Sat, Aug 21, 2010 at 11:02:54PM +0300, Gleb Natapov wrote:
On Sat, Aug 21, 2010 at 03:12:32PM -0400, Kevin O'Connor wrote:
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).
Can you explain why? What CMD_FORMAT is suppose to do? May be it is just a nop for virtio disk and returning success is much better in this case.
I believe format is supposed to write out the track info on floppy disks and such.
The ata spec still has a format command in it - though I wouldn't be surprised if modern drives didn't do anything when given that command. (The SeaBIOS ATA code returns success on CMD_FORMAT - see process_ata_misc_op().)
I'm not sure how calling code will react to getting a EWRITEPROTECT on format but success on a write. For consistency, I think it should either succeed on both or fail on both.
I don't think we need to actually implement virtio format code - a nop should be fine (just like what ata does).
-Kevin