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Date: Mon, 24 Apr 2006 10:38:56 +0200
From: Dan Sandberg <dan.sandberg@medsci.uu.se>
Subject: Re: [Qemu-devel] -kernel-kqemu - bug with -m 256
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To: qemu-devel@nongnu.org

Brad Campbell wrote:

> Troy Benjegerdes wrote:
>
>> On Thu, Feb 09, 2006 at 04:01:34PM -0600, Anthony Liguori wrote:
>>
>>> Jim C. Brown wrote:
>>>
>>>> -kernel-kqemu virtualizes ring 0 code.
>>>>
>>>> So it basically makes qemu do what VMware does.
>>>>
>>>> IIRC someone reported a 33% speedup with the new option.
>>>>  
>>>
>>> That was me.  That was a 33% speedup on win2k startup time.  kqemu 
>>> (user only) has a negligible impact on win2k startup time which 
>>> suggests this is mostly ring 0 code running which would make it a 
>>> good benchmark for kernel-kqemu performance.
>>>
>>> This was a terribly unscientific benchmarking so don't read too much 
>>> into it.
>>>
>>> Regards,
>>>
>>> Anthony Liguori
>>
>>
>> My win2k guest (with SP4, but not any updates) seemed to hang on startup
>> with -kernel-kqemu.
>
>
> Are you using -m 256 by any chance? I get this result with around that 
> much ram allocated to the guest. -m 160 (or less) or -m 384 (or more) 
> works perfectly here..
>
>
>
Great tip -thank you!

I have been having the same headache as others: Linux and RectOS guests 
constantly crashing in the very same spot when -kernel-kqemu is enabled.
I just made a quick test adding -m 384 and ReactOS suddenly boots all 
the way with -kernel-kqemu enabled!
My test line was:
qemu.exe -kernel-kqemu -m 384 -L ./bios -boot c -hda c.img

Best regards,
Dan Sandberg