[Qemu-devel] [Bug 1622582] Re: Can't install Windows 7 with q35 (SATA)

[John Snow <1622582@bugs.launchpad.net>]

** Changed in: qemu
       Status: New => Confirmed

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https://bugs.launchpad.net/bugs/1622582

Title:
  Can't install Windows 7 with q35 (SATA)

Status in QEMU:
  Confirmed

Bug description:
  I'm trying to install Windows 7 on a q35 machine on a "SATA disk". If
  I use q35 the installation is extremely slow. With extremely slow I
  mean, that the first few minutes (10-15 minutes) on the second
  installation step (copying files to disk) nothing happens. Than there
  is some progress, maybe until 9% and than there is "silence" for
  another 10 minutes or so. Therefore I used iotop (with --only option)
  in order to see, if there are any disk operations. But as I mentioned,
  only a few times qemu writes something to disk (with about < 1M/s).
  But most of the time there is nothing from qemu. Therefore the
  installation lasts over an hour. But even worse, after installation I
  can't boot Windows. Windows-Start-Manager tells me, that windows
  couldn't be loaded because the kernel is missing or corrupt (Status
  0xc0000221, File: \Windows\system32\ntoskrnl.exe). If I use IDE on q35
  or pc-i440fx-2.6 everything works fine. There is a continuous
  installation progress and iotop shows continuous disk writes with max
  30M/s (but also 5M/s and other values...).

  I've tried qemu 2.6.0, 2.6.1 and 2.7.0 (all versions from git).

  My host machine: 
  Ubuntu 14.04.5 LTS
  3.13.0-95-generic #142-Ubuntu SMP Fri Aug 12 17:00:09 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux
  Intel(R) Core(TM) i5-3470 CPU
  16 GB RAM

  
  I used the following commands:

  "Standard" command
  qemu-system-x86_64 -m 2048 -machine q35,accel=kvm -cpu host,kvm=off -smp 1,sockets=1,cores=1,threads=1 -enable-kvm -hda win7_qemu_standard_q35.qcow2 -cdrom win7proX64.iso -boot order=d

  I think by using -hda sata will be used?!?

  With explicit ahci:
  qemu-system-x86_64 -m 2048 -machine q35,accel=kvm -cpu host,kvm=off -smp 1,sockets=1,cores=1,threads=1 -enable-kvm -drive file=win7_qemu_standard_q35.qcow2,media=disk,if=none,id=sata-disk -device ich9-ahci,id=ahci -device ide-drive,drive=sata-disk,bus=ahci.0 -drive file=win7proX64.iso,media=cdrom,if=none,id=sata-cdrom -device ide-cd,drive=sata-cdrom,bus=ahci.1 -boot order=d

  I don't know if this is totally correct, because it's a little bit
  weird that I have to use ide-drive on a ich9 bus.

  Without kvm there is a continious disk write with 100 K/s - 5 M/s (works only with qemu 2.7.0, otherwise I get a 0x000000D1 bluescreen on the setup start screen):
  qemu-system-x86_64 -m 2048 -machine q35 -cpu IvyBridge -hda win7_qemu_standard_q35.qcow2 -cdrom win7proX64.iso -boot order=d

  But with all three commands the installed Windows is not working,
  because always the same error occurs: windows couldn't be loaded
  because kernel is missing or corrupt

  Interestingly both commands ("standard" command and with explicit
  ahci) works very well with a Windows 10 installation.

  In my opinion it's a "SATA problem", because if I use e.g. piix4-ide instead of ich9-ahci it works:
  qemu-system-x86_64 -m 2048 -machine q35,accel=kvm -cpu host,kvm=off -smp 1,sockets=1,cores=1,threads=1 -enable-kvm -drive file=win7_qemu_standard_q35.qcow2,media=disk,if=none,id=ide-disk -device piix4-ide,id=ide -device ide-drive,drive=ide-disk,bus=ide.0 -drive file=win7proX64.iso,media=cdrom,if=none,id=ide-cdrom -device ide-cd,drive=ide-cdrom,bus=ide.1 -boot order=d

  With this command there is a continuous disk write and the
  installation is bootable.

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