Re: [Qemu-devel] [PATCH] ATA: Allow WIN_SECURITY_FREEZE_LOCK as nop

[Alexander Graf]

On 09.02.2012, at 15:28, Kevin Wolf wrote:

> Am 30.01.2012 23:29, schrieb Alexander Graf:
>> When using Windows 8 with an AHCI disk drive, it issues a blue screen.
>> The reason is that WIN_SECURITY_FREEZE_LOCK / CFA_WEAR_LEVEL is not
>> supported by our ATA implementation, but Windows expects it to be there.
> 
> Is there anything that makes Windows believe that we support it? The
> spec says bits in IDENTIFY word 82 and 128 must be set to indicate
> support for the security feature set, and we don't set those.
> 
> Might be just a Windows bug, of course...

IIUC it's mandatory in more recent ATA versions, so that's probably why it 
assumes it's there.

> 
>> Since without security stuff implemented, the lock would be a nop anyway
>> and CFA_WEAR_LEVEL already is treated as a nop, let's just allow the cmd
>> for HD drives as well. That way Windows is happy.
> 
> It sets the sector count register to 0, which isn't exactly nop. In any
> case, the code would at the very least need a comment that it's used for
> two separate commands, so that we still remember this when some time in
> the future someone writes a real implementation.

Hrm. Good point.


Alex