debian/patches/ahci-properly-reset-pxcmd.patch

   1 While testing q35, I found that windows 7 (specifically, windows 7 ultimate
   2 with sp1 x64), wouldn't install because it can't find the cdrom or disk drive.
   3 The failure message is: 'A required cd/dvd device driver is missing. If you
   4 have a driver floppy disk, CD, DVD, or USB flash drive, please insert it now.'
   5 This can also be reproduced on piix by adding an ahci controller, and
   6 observing that windows 7 does not see any devices behind it.
   7
   8 The problem is that when windows issues a HBA reset, qemu does not reset the
   9 individual ports' PxCMD register. Windows 7 then reads back the PxCMD register
  10 and presumably assumes that the ahci controller has already been initialized.
  11 Windows then never sets up the PxIE register to enable interrupts, and thus it
  12 never gets irqs back when it sends ata device inquiry commands.
  13
  14 I believe this change brings qemu into ahci 1.3 specification compliance.
  15
  16 Section 10.4.3 HBA Reset:
  17
  18 "
  19 When GHC.HR is set to '1', GHC.AE, GHC.IE, the IS register, and all port
  20 register fields (except PxFB/PxFBU/PxCLB/PxCLBU) that are not HwInit in the
  21 HBA's register memory space are reset.
  22 "
  23
  24 I've also re-tested Fedora 16 and 17 to verify that they continue to work with
  25 this change.
  26
  27 Signed-off-by: Jason Baron <address@hidden>
  28 ---
  29  hw/ide/ahci.c |    1 +
  30  1 files changed, 1 insertions(+), 0 deletions(-)
  31
  32 Index: new/hw/ide/ahci.c
  33 ===================================================================
  34 --- new.orig/hw/ide/ahci.c      2012-09-24 07:15:28.000000000 +0200
  35 +++ new/hw/ide/ahci.c   2012-09-24 07:15:29.000000000 +0200
  36 @@ -1199,6 +1199,7 @@
  37          pr->irq_stat = 0;
  38          pr->irq_mask = 0;
  39          pr->scr_ctl = 0;
  40 +        pr->cmd = 0;
  41          ahci_reset_port(s, i);
  42      }
  43  }