Re: [PATCH] Simple brk allocator for very early allocations
From: Jeremy Fitzhardinge
Date: Sat Feb 28 2009 - 01:30:29 EST
Andrew Morton wrote:
On Fri, 27 Feb 2009 17:51:17 -0800 Jeremy Fitzhardinge <jeremy@xxxxxxxx> wrote:
This series adds a very simple brk-like allocator for very early
allocations. By default it extends the bss segment, starting at _end.
This is used to allocate x86-32's initial head_32.S pagetable, removing
init_pg_table_start/end and pg0, replacing them with brk allocations.
Changelog fails to provide a reason for this?
Well, the whole thing is just a generalization of what the 32-bit
pagetable builder does anyway, to make it more useful. With the brk
allocator in place, there's no reason for head_32.S to do it again.
dmi_alloc() is also changed to use extend_brk.
Seems a large patchset just to clean up DMI a bit ;)
A few patches could be folded together. But its pretty small really...
I assume that xen needs this? domU or dom0
I can make use of it in Xen to remove a bunch of static arrays. I'm
pretty sure there's quite a few places around the kernel which could
make use of this facility. My kernel has 900k of bss; how much of that
is stuff that 1) could be allocated, and 2) not actually being used at
runtime? A lot of things which are compile-time sized, hash tables, log
buffers, etc, could be runtime sized instead.
J
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