Re: [PATCH] x86_64: early memtest to find bad ram

From: Yinghai Lu
Date: Fri Mar 21 2008 - 17:43:22 EST


On Fri, Mar 21, 2008 at 2:22 PM, Jan Engelhardt <jengelh@xxxxxxxxxxxxxxx> wrote:
>
> On Mar 21 2008 13:03, Ingo Molnar wrote:
> > * Yinghai Lu <yhlu.kernel.send@xxxxxxxxx> wrote:
> >
> >> do simple memtest after init_memory_mapping
> >> use find_e820_area_size to find all ram range that is not reserved.
> >> and do some simple bits test to find some bad ram.
> >> if find some bad ram, use reserve_early to exclude that range.
> >
> > very nice patch! I always thought that this was the proper way to do
> > memtest - and we could in fact also do something like this after SMP
> > bringup, and hit the memory bus via multiple CPUs. [that will need a
> > different enumeration though than e820 maps]
>
> Perhaps this can even be used to provide on-the-fly badram
> patch semantics?

yes. but bad ranges can not be too many. otherwise early_res array
will overflow. then need to use memmap=nn$ss to exclude range already
found.

YH
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