On 30.08.2012, at 12:59, Jason Baron <jba...@redhat.com> wrote:
> On Fri, Aug 24, 2012 at 06:39:02AM +0200, Alexander Graf 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. >>> >>> I believe 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. >> >> What a nasty little bug. If it makes it work for you, the change is all fine >> from my POV (and should go into 1.2). >> > > Ok, I don't see it 1.2.0-rc2. If others are ok with this for 1.2, whose > tree should this go through? Kevin :) Alex > > Thanks, > > -Jason
