RE: [Xen-ia64-devel] [PATCH][RFC]discontig memory support

["Tian, Kevin" <kevin.tian@xxxxxxxxx>]

>From:Kouya SHIMURA
>Sent: 2006年4月4日 10:02
> > At least it is referenced.
> > You should remove these references and rename it.
>
>I know. swapper_pg_dir is referenced from vhpt_miss and
>nested_dtlb_miss in ivt.S.
>
>But the reference is obviously wrong. The code expects the physical
>address of swapper_pg_dir but the value is virtual. If these
>instructions are executed, an Unimplemented Data Address fault is
>raised.

In current xen/ia64 world, vhpt_miss and nested_dtlb_miss never happen 
and thus those paths are never executed in normal cases. However it's 
possible to enter those paths at some problematic environment, which 
may trigger more weird/nested faults. For example, one bug that people 
ever faced was that vhpt table was not TR mapped at context switch. So 
for safety, it's better for you to rename with a new one. And yes, vhpt_miss 
and nested_dtlb_miss handler needs to be cleared. Maybe with a simple 
panic loop there.

Thanks
Kevin

>
>Linux's ia64_patch_vtop() translates these virtual addresses to
>physical addreses on boot but Xen's ia64_patch_vtop() does nothing. :-<
>
>Anyway, I will rename it.
>
>Thanks,
>Kouya
>
>
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