Re: [Qemu-devel] [PATCH v2] ahci: properly reset PxCMD on HBA reset

[Kevin Wolf]

Am 05.09.2012 05:28, schrieb Alexander Graf:
> 
> On 04.09.2012, at 16:08, Jason Baron wrote:
> 
>> While testing q35, I found that windows 7 (specifically, windows 7 ultimate
>> with sp1 x64), wouldn't install because it can't find the cdrom or disk 
>> drive.
>> The failure message is: 'A required cd/dvd device driver is missing. If you
>> have a driver floppy disk, CD, DVD, or USB flash drive, please insert it 
>> now.'
>> This can also be reproduced on piix by adding an ahci controller, and
>> observing that windows 7 does not see any devices behind it.
>>
>> The problem is that when windows issues a HBA reset, qemu does not reset the
>> individual ports' PxCMD register. Windows 7 then reads back the PxCMD 
>> register
>> and presumably assumes that the ahci controller has already been initialized.
>> Windows then never sets up the PxIE register to enable interrupts, and thus 
>> it
>> never gets irqs back when it sends ata device inquiry commands.
>>
>> This change brings qemu into ahci 1.3 specification compliance.
>>
>> Section 10.4.3 HBA Reset:
>>
>> "
>> When GHC.HR is set to '1', GHC.AE, GHC.IE, the IS register, and all port
>> register fields (except PxFB/PxFBU/PxCLB/PxCLBU) that are not HwInit in the
>> HBA's register memory space are reset.
>> "
>>
>> I've also re-tested Fedora 16 and 17 to verify that they continue to work 
>> with
>> this change.
>>
>> Signed-off-by: Jason Baron <address@hidden>
> 
> Awesome, a lot cleaner now :).
> 
> Acked-by: Alexander Graf <address@hidden>

Thanks, applied to block-next.

Kevin