[PATCH] x86: Fix hwpoison code related build failure on 32-bitNUMAQ

[Ingo Molnar]

* Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:

> On Sat, 26 Sep 2009, Andi Kleen wrote:
> > 
> > Thanks for the report. The issue comes from NODES_SHIFT=4
> > 
> > I think I tested the NUMA case, but perhaps not with full NODES_SHIFT.
> > 
> > The easy fix would be to limit NODES_SHIFT to 3 for 32bit (8 nodes max). Do you
> > have any problems with that? I doubt there are any >8 nodes NUMAQs left.
> > (last time I heard the last machine at IBM was down to < 4)
> 
> No, just say "we don't support HWPOISON on 32-bit NUMA". 
> 
> Maybe simply using something like this.
> 
> TOTALLY UNTESTED!
> 
> 		Linus
> ---
>  arch/x86/Kconfig |    6 ++++++
>  mm/Kconfig       |    4 +++-
>  2 files changed, 9 insertions(+), 1 deletions(-)
> 
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index 9369879..be1bb44 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -432,6 +432,12 @@ config X86_NUMAQ
>  	  of Flat Logical.  You will need a new lynxer.elf file to flash your
>  	  firmware with - send email to <Martin.Bligh@xxxxxxxxxx>.
>  
> +config X86_SUPPORTS_MEMORY_FAILURE
> +	bool
> +	depends on !X86_NUMAQ
> +	select ARCH_SUPPORTS_MEMORY_FAILURE
> +	default y

Thanks Linus, this patch fixed the NUMAQ build problem.

Meanwhile i also found another similar build problem: sparsemem alone 
triggers the build bug on 32-bit as well:

 CONFIG_ARCH_SPARSEMEM_ENABLE=y
 CONFIG_SPARSEMEM_MANUAL=y
 CONFIG_SPARSEMEM=y
 CONFIG_SPARSEMEM_STATIC=y

So i added that to the X86_SUPPORTS_MEMORY_FAILURE rules as well - with 
that it works fine. (and this validates the concept of your patch as we 
keep excluding a new kernel feature in a well-documented way instead of 
narrowing existing hardware support with much less clear dependencies.)

I've attached the updated patch and will keep testing it a bit more 
(there might be more corner cases). If it goes fine i can send it to you 
via x86/urgent later today so that it gets into -rc1.

Can i add your signoff?

	Ingo


------------------->