Re: [Crash-utility] Re: [Xen-devel] crash can't analyze memory dumpfile of Xen

[Itsuro ODA <oda@xxxxxxxxxxxxx>]

Hi,

It is a good point. 
Thank you for your suggestion.

Itsuro Oda

On Fri, 03 Oct 2008 08:47:28 -0400
Dave Anderson <anderson@xxxxxxxxxx> wrote:

> Itsuro ODA wrote:
> > Hi,
> > 
> > I found the root cause of this problem is that the value of "PERCPU_SHIFT"
> > was changed to 13 from 12.
> > 
> > The quick workaround is to apply the following patch to the crash command:
> > ----------------------------------------------------------------------
> > --- xen_hyper_defs.h.org        2008-10-03 14:46:28.000000000 +0900
> > +++ xen_hyper_defs.h    2008-10-03 14:46:50.000000000 +0900
> > @@ -134,7 +134,7 @@
> >  #endif
> > 
> >  #if defined(X86) || defined(X86_64)
> > -#define XEN_HYPER_PERCPU_SHIFT 12
> > +#define XEN_HYPER_PERCPU_SHIFT 13
> >  #define xen_hyper_per_cpu(var, cpu)  \
> >         ((ulong)(var) + (((ulong)(cpu))<<XEN_HYPER_PERCPU_SHIFT))
> >  #elif defined(IA64)
> > ------------------------------------------------------------------------
> > 
> > I need to think the backword compatibility. I wonder how to determine
> > the value of "PERCPU_SHIFT". The change of "PERCPU_SHIFT" was made at
> > a certain point of xen-unstable before xen-3.3 release. The xen version
> > number (3.3) can't use as key... I will consider more...
> 
>  From the crash utility perspective, and looking at the RHEL5 xen sources
> where these hypervisor definitions exist:
> 
>    #define PERCPU_SIZE (1UL << PERCPU_SHIFT)
> 
>    static void __init percpu_init_areas(void)
>    {
>        unsigned int i, data_size = __per_cpu_data_end - __per_cpu_start;
>        unsigned int first_unused;
> 
>        BUG_ON(data_size > PERCPU_SIZE);
> 
> during initialization you could calculate the difference between the
> __per_cpu_data_end and __per_cpu_start symbol values, and if it's more
> than the original 4k size (12), then it must be 13.
> 
> Dave
> 
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-- 
Itsuro ODA <oda@xxxxxxxxxxxxx>


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