CPU change causes hanging of .NET apps

CPU change causes hanging of .NET apps

[Erik Rull]

Hi all,

when changing the CPU from the default QEMU32 one to e.g. the n270 or the 
core2duo no .NET apps will work under Windows XP as guest. Switching back 
and everything is fine. The Pentium Emulation on the other side works fine!

The Application loads but it hangs with 99% CPU usage and ca. 3-4 MB Memory 
  Consumption.

Normally, .NET is capable to run on all x86 Processors >= Pentium. XP and 
non-.NET Apps work fine.

Any Ideas what happens here? I also started applications that were NOT 
started with the QEMU32 CPU to prevent a caching - same problem.

Best regards,

Erik

Re: CPU change causes hanging of .NET apps

[Javier Guerra]

On Wed, Oct 28, 2009 at 4:13 PM, Erik Rull <erik.rull@rdsoftware.de> wrote:
> Any Ideas what happens here? I also started applications that were NOT
> started with the QEMU32 CPU to prevent a caching - same problem.

just a couple guesses:

- maybe there's some JIT'ed code cached somewhere in the filesystem

- maybe the exact code generator is chosen at startup time, or even at
.NET installation time.

in short, if restarting windows doesn't fix it, i would reinstall
.NET, or maybe the whole HAL

-- 
Javier

Re: CPU change causes hanging of .NET apps

[Brian Jackson]

On Wednesday 28 October 2009 16:13:37 Erik Rull wrote:
> Hi all,
> 
> when changing the CPU from the default QEMU32 one to e.g. the n270 or the
> core2duo no .NET apps will work under Windows XP as guest. Switching back
> and everything is fine. The Pentium Emulation on the other side works fine!


Have you tried with -cpu core2duo,-nx ?

--Iggy


> 
> The Application loads but it hangs with 99% CPU usage and ca. 3-4 MB Memory
>   Consumption.
> 
> Normally, .NET is capable to run on all x86 Processors >= Pentium. XP and
> non-.NET Apps work fine.
> 
> Any Ideas what happens here? I also started applications that were NOT
> started with the QEMU32 CPU to prevent a caching - same problem.
> 
> Best regards,
> 
> Erik
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Re: CPU change causes hanging of .NET apps

[Avi Kivity]

On 10/28/2009 11:13 PM, Erik Rull wrote:
> Hi all,
>
> when changing the CPU from the default QEMU32 one to e.g. the n270 or 
> the core2duo no .NET apps will work under Windows XP as guest. 
> Switching back and everything is fine. The Pentium Emulation on the 
> other side works fine!
>
> The Application loads but it hangs with 99% CPU usage and ca. 3-4 MB 
> Memory  Consumption.
>
> Normally, .NET is capable to run on all x86 Processors >= Pentium. XP 
> and non-.NET Apps work fine.
>
> Any Ideas what happens here? I also started applications that were NOT 
> started with the QEMU32 CPU to prevent a caching - same problem.
>

What's your host cpu type?

-- 
error compiling committee.c: too many arguments to function

Re: CPU change causes hanging of .NET apps

[Erik Rull]

Hi Avi,

the Host CPU is a Intel Core2Duo - VT capable and enabled!

Best regards,

Erik


Avi Kivity wrote:
> On 10/28/2009 11:13 PM, Erik Rull wrote:
>> Hi all,
>>
>> when changing the CPU from the default QEMU32 one to e.g. the n270 or 
>> the core2duo no .NET apps will work under Windows XP as guest. 
>> Switching back and everything is fine. The Pentium Emulation on the 
>> other side works fine!
>>
>> The Application loads but it hangs with 99% CPU usage and ca. 3-4 MB 
>> Memory  Consumption.
>>
>> Normally, .NET is capable to run on all x86 Processors >= Pentium. XP 
>> and non-.NET Apps work fine.
>>
>> Any Ideas what happens here? I also started applications that were NOT 
>> started with the QEMU32 CPU to prevent a caching - same problem.
>>
> 
> What's your host cpu type?
> 

Re: CPU change causes hanging of .NET apps

[Avi Kivity]

On 11/02/2009 01:45 AM, Erik Rull wrote:
> Hi Avi,
>

Please don't top-post.

> the Host CPU is a Intel Core2Duo - VT capable and enabled!

The problem is that one of the flags that -cpu core2duo enables is 
implemented incorrectly, so it leads to .net breakage.

These flags are pni, lm, nx, ssse3, syscall.

Please try -cpu core2duo,-pni,-lm,-nx,-ssse3,-syscall.  If it works, 
remove features one by one until it doesn't and let us know the results.

-- 
Do not meddle in the internals of kernels, for they are subtle and quick to panic.

Re: CPU change causes hanging of .NET apps

[Erik Rull]

Avi Kivity wrote:
> On 11/02/2009 01:45 AM, Erik Rull wrote:
>> Hi Avi,
>>
> 
> Please don't top-post.
> 
>> the Host CPU is a Intel Core2Duo - VT capable and enabled!
> 
> The problem is that one of the flags that -cpu core2duo enables is 
> implemented incorrectly, so it leads to .net breakage.
> 
> These flags are pni, lm, nx, ssse3, syscall.
> 
> Please try -cpu core2duo,-pni,-lm,-nx,-ssse3,-syscall.  If it works, 
> remove features one by one until it doesn't and let us know the results.

I took all flags, same effect as without all of these flags.  :(

Any other idea?

- Erik

Re: CPU change causes hanging of .NET apps

[Avi Kivity]

On 11/03/2009 04:56 PM, Erik Rull wrote:
>
> I took all flags, same effect as without all of these flags.  :(
>
> Any other idea?

It's probably the cache size query.

Does -cpu host work?

-- 
error compiling committee.c: too many arguments to function

Re: CPU change causes hanging of .NET apps

[Timur Safin]

2009/11/3 Avi Kivity <avi@redhat.com>:
> On 11/03/2009 04:56 PM, Erik Rull wrote:
>>
>> I took all flags, same effect as without all of these flags.  :(
>>
>> Any other idea?
>
> It's probably the cache size query.
>
> Does -cpu host work?
>

My totally noob in QEMU guess -
my bet it's CR4.OSFXSR which is controlled by presence of
cpuid.1.edx[24] - FXSR bit (FXSAVE and FXRSTOR) instructions.

I'm curious - is there any way in QEMU to redefine returned cpuid leaf
values? It will be interesting to see results if that given bit will
be disabled in configuration.

Best Regards,
Timur

Re: CPU change causes hanging of .NET apps

[Avi Kivity]

On 11/03/2009 05:11 PM, Timur Safin wrote:
>
> My totally noob in QEMU guess -
> my bet it's CR4.OSFXSR which is controlled by presence of
> cpuid.1.edx[24] - FXSR bit (FXSAVE and FXRSTOR) instructions.
>    

That would affect floating point as well.

> I'm curious - is there any way in QEMU to redefine returned cpuid leaf
> values? It will be interesting to see results if that given bit will
> be disabled in configuration.
>    

qemu -cpu host,-flag

-- 
error compiling committee.c: too many arguments to function

Re: CPU change causes hanging of .NET apps

[Erik Rull]

Avi Kivity wrote:
> On 11/03/2009 05:11 PM, Timur Safin wrote:
>>
>> My totally noob in QEMU guess -
>> my bet it's CR4.OSFXSR which is controlled by presence of
>> cpuid.1.edx[24] - FXSR bit (FXSAVE and FXRSTOR) instructions.
>>    
> 
> That would affect floating point as well.
> 
>> I'm curious - is there any way in QEMU to redefine returned cpuid leaf
>> values? It will be interesting to see results if that given bit will
>> be disabled in configuration.
>>    
> 
> qemu -cpu host,-flag
> 

I tried that value, result is an error:
Unable to find x86 CPU definition

- Erik

Re: CPU change causes hanging of .NET apps

[Avi Kivity]

On 11/05/2009 09:03 PM, Erik Rull wrote:
>> qemu -cpu host,-flag
>>
>
>
> I tried that value, result is an error:
> Unable to find x86 CPU definition

Please use qemu-kvm.git for this test.

-- 
error compiling committee.c: too many arguments to function