Re: [PATCH] [18/18] Implement hugepagesz= option for x86-64

From: Andi Kleen
Date: Mon Mar 17 2008 - 06:00:14 EST


On Mon, Mar 17, 2008 at 04:29:39AM -0500, Paul Jackson wrote:
> Andi wrote:
> + hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
> + hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
> + On x86 this option can be specified multiple times
> + interleaved with hugepages= to reserve huge pages
> + of different sizes. Valid pages sizes on x86-64
> + are 2M (when the CPU supports "pse") and 1G (when the
> + CPU supports the "pdpe1gb" cpuinfo flag)
> + Note that 1GB pages can only be allocated at boot time
> + using hugepages= and not freed afterwards.
>
> This seems to say that hugepages are required for hugepagesz to be

Yes, but that was already there before. I didn't change it.

I agree it should be fixed, but i would prefer to not mix
PPC specific patches into my patchkit so I hope someone
else will do that afterwards.

> useful, but hugepagesz is supported on PPC, whereas hugepages is not
> supported on PPC ...odd.
>
> Should those two HW lists be the same (and sorted in the same order,
> for ease of reading)?

Not all architectures support hugepagesz=, in particular i386
does not and possibly others. It is implemented by arch specific
code.

-Andi
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