Re: 2.6.27rc1 cannot boot more than 8CPUs

[Ingo Molnar]

* Jeff Chua <jeff.chua.linux@xxxxxxxxx> wrote:

>
> On Wed, Aug 6, 2008 at 5:42 PM, Jeff Chua <jeff.chua.linux@xxxxxxxxx>  
> wrote:
>>>> CONFIG_X86_GENERICARCH=y
>>>> CONFIG_X86_BIGSMP=y
>>>> 8 more cpu need bigsmp mode.
>
>> Just found it under " Subarchitecture Type (Generic architecture)",
>> and then it shows the CONFIG_X86_BIGSMP option.
>
> It works. Booted with 16CPUs. 32GB RAM.
>
> CPU0 L7345 1.86GHz  0C
> CPU1 L7345 1.86GHz  0C
> CPU2 L7345 1.86GHz  0C
> CPU3 L7345 1.86GHz  0C
> CPU4 L7345 1.86GHz  0C
> CPU5 L7345 1.86GHz  0C
> CPU6 L7345 1.86GHz  0C
> CPU7 L7345 1.86GHz  0C
> CPU8 L7345 1.86GHz  0C
> CPU9 L7345 1.86GHz  0C
> CPU10 L7345 1.86GHz  0C
> CPU11 L7345 1.86GHz  0C
> CPU12 L7345 1.86GHz  0C
> CPU13 L7345 1.86GHz  0C
> CPU14 L7345 1.86GHz  0C
> CPU15 L7345 1.86GHz  0C
>
>
> So, but setting the config not obvious. And should CONFIG_X86_PC be  
> considered as well as CONFIG_X86_GENERICARCH?
>
> With CONFIG_X86_PC, I can set CONFIG_SPARSEMEM=y.
>
> With CONFIG_X86_GENERICARCH, CONFIG_SPARSEMEM depends on CONFIG_NUMA.
>
> I'm using the patch below to enable sparsemem instead of flatmem, but  
> don't know what impact it has. System booted and running.
>
> It would be nice to automatically default CONFIG_X86_BIGSMP with CPUs 
> > 8. But I don't know to do that.

thanks, applied.

i'm wondering, does with that patch applied a working 2.6.26 .config if 
put through 'make oldconfig' boot fine on your box now? Any make 
oldconfig breakage is a regression we want to fix. We want upgrades 
between kernel versions to be seemless and complete.

	Ingo
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