Re: [Qemu-devel] Qemu / KQemu on 64-bit (x86_64) host systems

[Werner Dittmann <Werner.Dittmann@t-online.de>]

Andrzej,

setting "notsc" makes the difference (yesterday I forgot to start
lilo after modifying /etc/lilo.conf to include notsc"). Now it
work even with -kernel-kqemu. Not fully tested though, but much
better than before.

Thanks,
Werner


andrzej zaborowski wrote:
> Hi,
> 
> On 17/04/07, Werner Dittmann <Werner.Dittmann@t-online.de> wrote:
>> andrzej zaborowski wrote:
>> > Hi,
>> >
>> > On 16/04/07, Werner Dittmann <Werner.Dittmann@t-online.de> wrote:
>> >> During several tests with Qemu / Kqemu it seems that Qemu
>> >> has problems with x86_64 host systems. My system is an
>> >> AMD 64 X2 (Dual Core), running openSUSE 10.2, 2GB memory.
>> >>
>> Indeed it is a dual CPU. Adding notsc as an additional parameter to
>> the kernel commandline (the guest system uses Lilo). Using this
>> parameter the kernel was able to start INIT and the init.d startup
>> scripts (not always, but most of the time). After a short time
>> the kernel starts to loop again, e.g. during hotplug handling.
> 
> Hmm, I was thinking that it may be the same problem as I described in
> http://lists.gnu.org/archive/html/qemu-devel/2007-03/msg00652.html but
> if the lockup is happening anyway then I'm not sure. On the other hand
> "notsc" does make a difference, right?
> 
>>
>> Using th same technique as before (gdb) it's the same picture:
>> mainly in compute_c_subl or compute_c_addl.
>>
>> >
>> > Does your host happen to be dual-core? If so, please try adding
>> > "notsc" to the guest kernel commandline and report if it makes a
>> > difference.
>> >
>> >>
>> I thought qemu's gdb server is used to debug kernels running
>> inside Qemu but not to debug Qemu itself. IMHO the problem is not
>> in the kernel (the kernel works perfectly on a real HW processor)
>> but in Qemu.
> 
> That's right, qemu's gdb server is for debugging the guest. However,
> it's often much easier to debug qemu knowing what guest code is
> causing the qemu bug, especially C code in case of opensource guests,
> and especially a guest lockup or guest crash.
> 
> Other than that I think there's only the -d.
> 
> Regards,
> Andrzej
> 
> 
>