Re: [PATCH 0/8] x86, acpi: Move acpi_initrd_override() earlier.

[Tejun Heo <tj@kernel.org>]

Hello,

On Thu, Aug 22, 2013 at 02:11:32PM -0600, Toshi Kani wrote:
> It's too late for the kernel image itself, but it prevents allocating
> kernel memory from movable ranges after that.  I'd say it solves a half
> of the issue this time.

That works if such half solution eventually leads to the full
solution.  This is just a distraction.  You are already too late in
the boot sequence.  It doesn't even qualify as a half solution.  It's
like obsessing about a speck on your shirt without your trousers on.
If you want to solve this, do that from a place where it actually is
solvable.

> > > Also, how do you support local page tables without pursing SRAT early?
> > 
> > Does it even matter with huge mappings?  It's gonna be contained in a
> > single page anyway, right?
> 
> Are the huge mappings always used?  We cannot force user programs to use
> huge pages, can we?

Everything is a trade-off.  Should we do all this just to support the
off chance someone tries to use memory hotplug on a machine which
doesn't support huge mapping when virtually all CPUs on market
supports it?

> As for the maintainability, I am far more concerned with your suggestion
> of having a separate page table init code when SRAT is used.  This kind
> of divergence is a recipe of breakage.

I don't buy that.  The only thing which needs to change is the
directionality of allocation and we probably don't even need to do
that if huge mapping is in use.

Thanks.

-- 
tejun

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