On 31.08.2012, at 07:23, Jason Baron wrote: > On Fri, Aug 31, 2012 at 12:12:22PM +0200, Kevin Wolf wrote: >> Am 23.08.2012 23:09, schrieb Jason Baron: >>> 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. >>> >>> Signed-off-by: Jason Baron <jba...@redhat.com> >>> --- >>> hw/ide/ahci.c | 1 + >>> 1 files changed, 1 insertions(+), 0 deletions(-) >>> >>> diff --git a/hw/ide/ahci.c b/hw/ide/ahci.c >>> index 9fe89a5..06c236f 100644 >>> --- a/hw/ide/ahci.c >>> +++ b/hw/ide/ahci.c >>> @@ -1199,6 +1199,7 @@ void ahci_reset(AHCIState *s) >>> pr->irq_stat = 0; >>> pr->irq_mask = 0; >>> pr->scr_ctl = 0; >>> + pr->cmd = 0; >>> ahci_reset_port(s, i); >>> } >>> } >>> >> >> In ahci_init() we have: >> >> ad->port_regs.cmd = PORT_CMD_SPIN_UP | PORT_CMD_POWER_ON; >> >> Why is resetting to 0 in ahci_reset() correct? I think we can still get >> this part committed for 1.2 after you either explain why 0 is right or >> send a fixed version. >> > > Good catch. I just tried out the following instead in ahci_reset(): > > pr->cmd = PORT_CMD_SPIN_UP | PORT_CMD_POWER_ON; > > And it continues to make Windows7 find the ahci disks. I'd like to do a > little more testing, but I will send an updated path.
Since we reset on init, we can just shove it there completely, right? Alex
