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. I think for 1.3 there's still a bit more left. We're missing some more fields in a reset: tfdata isn't set at all, should be set to 0x7f in ahci_reset_port(), and cmd_issue should be set to 0. And shouldn't ahci_init() actually call ahci_reset() in order to ensure consistent results? Kevin
