Re: 2.6.27rc1 cannot boot more than 8CPUs

Jeff Chua
2008-08-13T17:34:08Z

On Thu, Aug 14, 2008 at 1:10 AM, Jeff Chua <jeff.chua.linux@gmail.com> wrote:
> On Wed, Aug 13, 2008 at 10:16 PM, Ingo Molnar <mingo@elte.hu> wrote:
>
>> btw., could you please check that v2.6.27-rc3 (or later) kernels boot
>> fine (with about 8 cpus) even if you have genericarch/bigsmp disabled,
>> and do not silently hang as it happened on your box before?
>
> With 16 CPUs, it still hangs, but now the console is showing the
> errors as intended.
> ... but it is supposed to hang?

I tried with just CONFIG_NR_CPUS=8 and this time it booted, but stange
thing is I only see 2 CPUs! To be more precise, it's without both
CONFIG_X86_GENERICARCH and CONFIG_X86_BIGSMP.

And when I tried to enable the CPUs, it complained about:

# cat cpu6/online
0
# echo 1 > cpu6/online
More than 8 CPUs detected - skipping them.
Use CONFIG_X86_GENERICARCH and CONFIG_X86_BIGSMP.
-bash: echo: write error: Input/output error

Prior to the patch, the system booted with all 8 CPUs.

Again, if I enable both CONFIG_X86_GENERICARCH and CONFIG_X86_BIGSMP,
I get all 16 CPUs.

Thanks,
Jeff.