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SubjectRe: [PATCH 4/4] x86_64: increse MAX_EARLY_RES for NODE_DATA and bootmap
Date
On Thursday 31 January 2008 14:24:38 Ingo Molnar wrote:
>
> * Yinghai Lu <Yinghai.Lu@Sun.COM> wrote:
>
> > ok, discard 3, and 4.
> >
> > how about 2 v2?
>
> i'm leaning towards v4, but the more fundamental breakage is in the
> early_node_mem() ad-hoc allocator that got butchered into this code a
> year ago:

No it has nothing to do with early_node_mem which is just a thin
wrapper around find_e820_area() anyways.

I think the problem is that the page alignment in bad_addr() and friends is not
always correct. e.g. the early_reserve for the kernel in head64.c really need to
round up to pages. I suspect (not 100% sure yet that is the core of the problem)

Note this was broken even before early reservation; the only difference
was that it was all hard coded in bad_addr() then.

There were various hacks around this in the past, but none fixed the problem
completely.

> commit a8062231d80239cf3405982858c02aea21a6066a
> Author: Andi Kleen <ak@suse.de>
> Date: Fri Apr 7 19:49:21 2006 +0200
>
> [PATCH] x86_64: Handle empty PXMs that only contain hotplug memory
>
> ...
> +static void * __init
> +early_node_mem(int nodeid, unsigned long start, unsigned long end,
> + unsigned long size)
>
> and we are now suffering the side-effects of that hack.
>
> what i suspect we need instead is a proper early-allocator that works in
> the e820 space.

That is find_e820_area() or rather find_e820_area+early_reserve now.

I had this implemented as a shrink wrapped function earlier for lockdep too,
but dropped the patch because there was a nasty ordering issue with the e820
command line parsing that i could not easily resolve.

-Andi


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