Re: [Xen-devel] Ubuntu 10.04 stuck in detect_extended_topology()

[Jeremy Fitzhardinge <jeremy@xxxxxxxx>]

On 06/09/2010 02:55 PM, AP Xen wrote:
>
> I am running Xen packaged with CentOS 5.4 and trying to install Ubuntu
> 10.04 as an HVM guest.
>
>  
>
> xen_major              : 3
>
> xen_minor              : 1
>
> xen_extra              : .2-164.11.1.el5
>
>  
>
> After sprinkling the kernel with printks, I am seeing that it is stuck
> in the function detect_extended_topology() in the following loop:
>
> <snip>
>
>        sub_index = 1;
>
>        do {
>
>               cpuid_count(0xb, sub_index, &eax, &ebx, &ecx, &edx);
>
>               printk("%s: after cpuid_count %d\n", __FUNCTION__,
> sub_index);
>
>  
>
>               /*
>
>                * Check for the Core type in the implemented sub leaves.
>
>                */
>
>               if (LEAFB_SUBTYPE(ecx) == CORE_TYPE) {
>
>                      core_level_siblings = LEVEL_MAX_SIBLINGS(ebx);
>
>                      core_plus_mask_width = BITS_SHIFT_NEXT_LEVEL(eax);
>
>                      break;
>
>               }
>
>  
>
>               sub_index++;
>
>        } while (LEAFB_SUBTYPE(ecx) != INVALID_TYPE);
>
> <snip>
>
>  
>
> The ECX leaf subtype never returns CORE_TYPE or INVALID_TYPE. So think
> I might be running in to a bug / quirk in the CPUID handling code in
> Xen packaged with CentOS 5.4. Is there a work around for it? Maybe
> specifying something in the cpuid option in the config file.
>

What's the host cpu type?  You should be able to completely disable the
extended topology leaf (0xb) with the cpuid= directive in the config file.

    J

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