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Re: [Qemu-devel] Wierd hack to sound/pci/intel8x0.c
From: |
Takashi Iwai |
Subject: |
Re: [Qemu-devel] Wierd hack to sound/pci/intel8x0.c |
Date: |
Mon, 07 Nov 2011 11:44:23 +0100 |
User-agent: |
Wanderlust/2.15.6 (Almost Unreal) SEMI/1.14.6 (Maruoka) FLIM/1.14.9 (Gojō) APEL/10.7 Emacs/23.3 (x86_64-suse-linux-gnu) MULE/6.0 (HANACHIRUSATO) |
At Mon, 07 Nov 2011 10:25:24 +0100,
Gerd Hoffmann wrote:
>
> Hi,
>
> > Agreed. If we can know the virtual device for KVM in a better way
> > (e.g. any specific PCI SSID or such), we can narrow the condition more
> > safely.
>
> PCI Subsystem ID 1af4:1100 is qemu/kvm (not only Intel HDA, most other
> emulated pci devices have it too). Complete entry:
>
> 00:04.0 0403: 8086:2668 (rev 01)
> Subsystem: 1af4:1100
> Physical Slot: 4
> Flags: bus master, fast devsel, latency 0, IRQ 11
> Memory at e2030000 (32-bit, non-prefetchable) [size=16K]
> Kernel driver in use: HDA Intel
> Kernel modules: snd-hda-intel
Thanks.
BTW, this reminds me of a possible improvement in the current HD-audio
driver. It has some workaround for the delayed DMA-position update
(the DMA-position isn't completely updated when IRQ is issued) by
offsetting the buffer position. This is controlled by bdl_pos_adj
option of snd-hda-intel driver, and this could be zero for VMs.
Takashi
- Re: [Qemu-devel] Wierd hack to sound/pci/intel8x0.c, (continued)
- Re: [Qemu-devel] Wierd hack to sound/pci/intel8x0.c,
Takashi Iwai <=