Re: Booting/installing WindowsNT

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

Avi Kivity wrote:
> On 05/03/2010 11:24 AM, Andre Przywara wrote:
>>
>> can you try -cpu kvm64? This should be somewhat in between -cpu host 
>> and -cpu qemu64.
>> Also look in dmesg for uncatched rd/wrmsrs. In case you find something 
>> there, please try:
>> # modprobe kvm ignore_msrs=1
>> (You have to unload the modules first)
> 
> It's unlikely NT 4 will touch msrs, it's used to running on very old 
> hardware (pre-msr, even).  I expect it's a problem with the bios or 
> vendor/model/blah.
That is probably right, although I could be that it uses some MSRs if it 
finds the CPUID bit set. But I just wanted to make sure that not the issue.

I made a diff of the CPUID flags between qemu64 and Michael's host, the 
difference is:
only on qemu64: up hypervisor
up is a Linux pseudo flag for a SMP kernel running on an UP host, the 
hypervisor bit has been introduced much later than even SP6. I guess 
that is OK, but note that Linux supposedly recognizes the single VCPU 
guest with -cpu host as SMP. But I guess that is not an issue for NT4, 
since it does not know about multi-core CPUs and CPUID based topology 
detection.

only on host: vme ht mmxext fxsr_opt rdtscp 3dnowext 3dnow rep_good 
extd_apicid
cmp_legacy svm extapic cr8_legacy 3dnowprefetch lbrv 

Most of the features are far younger than NT4, only "vme" sticks out.
This is pretty old flag, but I am not sure if that matters. My 
documentation reads:
VME: virtual-mode enhancements. CR4.VME, CR4.PVI, software interrupt 
indirection, expansion of the TSS with the software, indirection bitmap, 
EFLAGS.VIF, EFLAGS.VIP.

Let's just rule that out:

Michael, can you try to use -cpu host,-vme and see if that makes a 
difference?

Thanks,
Andre.

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