Re: Booting/installing WindowsNT

[Andre Przywara <andre.przywara@amd.com>]

Michael Tokarev wrote:
> 05.05.2010 12:32, Andre Przywara wrote:
>> Avi Kivity wrote:
>>> On 05/04/2010 06:27 PM, Andre Przywara wrote:
>>>>
>>>>> 3. In all other cases so far it BSoDs with STOP 0x3E error
>>>>> right before displaying that kernel message.
>>>> MSDN talks about a mulitprocessor configuration error:
>>>> http://msdn.microsoft.com/en-us/library/ms819006.aspx
>>>> I suspected the offline CPUs in the mptable that confuse NT. But -smp
>>>> 1,maxcpus=1 does not make a difference. I will try to dig deeper in
>>>> this area.
>> OK, I tackled this down. It is the max CPUID level that differs.
>> In the AMD CPUID guide leafs 0000_0002 till 0000_0004 are reserved, the
>> CPU that Michael and I used (K8RevF) actually have a max leaf of 1 here.
>> Default qemu64 has a max leaf of 4.
>> So by saying -cpu qemu64,level=1 (or 2 or 3) it works for me.
>> Modern OS only read leaf 4 on Intel systems, it seems that NT4 is
>> missing this.
> 
> Confirmed, with -cpu qemu64,level=[123] it works for me as well.
The strange thing is that NT4 never reads leaf 4:
kvm-2341  [003]   228.527874: kvm_cpuid: func 40000000 rax 0 rbx 
4b4d564b rcx 564b4d56 rdx 4d
kvm-2341  [003]   228.530033: kvm_cpuid: func 1 rax 623 rbx 800 rcx 
80002001 rdx 78bfbfd
kvm-2341  [003]   228.530081: kvm_cpuid: func 80000000 rax 8000000a rbx 
68747541 rcx 444d4163 rdx 69746e65
kvm-2341  [003]   228.530084: kvm_cpuid: func 80000008 rax 3028 rbx 0 
rcx 0 rdx 0
kvm-2341  [003]   228.530147: kvm_cpuid: func 1 rax 623 rbx 800 rcx 
80002001 rdx 78bfbfd
kvm-2341  [002]   228.538254: kvm_cpuid: func 1 rax 623 rbx 800 rcx 
80002001 rdx 78bfbfd
kvm-2341  [002]   228.539902: kvm_cpuid: func 1 rax 623 rbx 800 rcx 
80002001 rdx 78bfbfd
kvm-2341  [002]   236.273370: kvm_cpuid: func 1 rax 623 rbx 800 rcx 
80002001 rdx 78bfbfd
kvm-2341  [002]   236.273381: kvm_cpuid: func 0 rax 4 rbx 68747541 rcx 
444d4163 rdx 69746e65

With level=4 it BSODs afterwards, with level=1 it beyond that:
kvm-2472  [002]   871.379192: kvm_cpuid: func 1 rax 623 rbx 800 rcx 
80002001 rdx 78bfbfd
kvm-2472  [002]   871.379235: kvm_cpuid: func 0 rax 1 rbx 68747541 rcx 
444d4163 rdx 69746e65
kvm-2472  [002]   871.379238: kvm_cpuid: func 1 rax 623 rbx 800 rcx 
80002001 rdx 78bfbfd
....

Interestingly it also accesses leaf 8000_0008, I thought that that leaf 
wasn't around in 1996.

> 
> Note again that after service pack 6 (I haven't tried other SPs),
> the problem goes away entirely -- winNT SP6 works with the default
> kvm cpu just fine.
I agree with Avi that it looks like a bug to me. I will see if I can 
learn more about it.

Regards,
Andre.

-- 
Andre Przywara
AMD-Operating System Research Center (OSRC), Dresden, Germany
Tel: +49 351 448-3567-12