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[Qemu-devel] HPET configuration in Seabios (was: Re: windows workload: m
From: |
Jan Kiszka |
Subject: |
[Qemu-devel] HPET configuration in Seabios (was: Re: windows workload: many ept_violation and mmio exits) |
Date: |
Sun, 28 Aug 2011 22:42:49 +0200 |
User-agent: |
Mozilla/5.0 (X11; U; Linux i686 (x86_64); de; rv:1.8.1.12) Gecko/20080226 SUSE/2.0.0.12-1.1 Thunderbird/2.0.0.12 Mnenhy/0.7.5.666 |
On 2011-08-28 20:54, Alexander Graf wrote:
>
> On 28.08.2011, at 02:42, Avi Kivity wrote:
>
>> On 08/26/2011 08:32 AM, ya su wrote:
>>> hi,Avi:
>>>
>>> I met the same problem, tons of hpet vm_exits(vector 209, fault
>>> address is in the guest vm's hpet mmio range), even I disable hpet
>>> device in win7 guest vm, it still produce a larget amount of vm_exits
>>> when trace-cmd ; I add -no-hpet to start the vm, it still has HPET
>>> device inside VM.
>>>
>>> Does that means the HPET device in VM does not depend on the
>>> emulated hpet device in qemu-kvm? Is there any way to disable the VM
>>> HPET device to prevent so many vm_exits? Thansk.
>>>
>>
>> Looks like a bug to me.
>
> IIRC disabling the HPET device doesn't remove the entry from the DSDT, no? So
> the guest OS might still think it's there while nothing responds (read
> returns -1).
Exactly. We have a fw_cfg interface in place for quite a while now
(though I wonder how the firmware is supposed to tell -no-hpet apart
from QEMU versions that don't provide this data - both return count =
255), but SeaBios still exposes one HPET block at a hard-coded address
unconditionally.
There was quite some discussion about the corresponding Seabios patches
back then but apparently no consensus was found. Re-reading it, I think
Kevin asked for passing the necessary DSDT fragments from QEMU to the
firmware instead of using a new, proprietary fw_cfg format. Is that
still the key requirement for any patch finally fixing this bug?
Jan
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- Re: [Qemu-devel] windows workload: many ept_violation and mmio exits, Alexander Graf, 2011/08/28
- [Qemu-devel] HPET configuration in Seabios (was: Re: windows workload: many ept_violation and mmio exits),
Jan Kiszka <=
- Re: [Qemu-devel] HPET configuration in Seabios (was: Re: windows workload: many ept_violation and mmio exits), Kevin O'Connor, 2011/08/28
- Re: [Qemu-devel] HPET configuration in Seabios, Avi Kivity, 2011/08/29
- Re: [Qemu-devel] HPET configuration in Seabios, Jan Kiszka, 2011/08/29
- Re: [Qemu-devel] HPET configuration in Seabios, Avi Kivity, 2011/08/29
- Re: [Qemu-devel] HPET configuration in Seabios, Jan Kiszka, 2011/08/29
- Re: [Qemu-devel] HPET configuration in Seabios, Avi Kivity, 2011/08/29
- Re: [Qemu-devel] HPET configuration in Seabios, Jan Kiszka, 2011/08/29