Re: [PATCH 2/3] FRV: Permit __do_IRQ() to be dispensed with

From: Ingo Molnar
Date: Mon Sep 11 2006 - 01:40:01 EST



* Daniel Walker <dwalker@xxxxxxxxxx> wrote:

> On Sat, 2006-09-09 at 07:12 +0200, Ingo Molnar wrote:
>
> > The real solution would be to use gcc -ffunction-sections plus ld
> > --gc-sections to automatically get rid of unused global functions, at
> > link time. I'm wondering how hard it would be to enhance kbuild to do
> > that - x86_64 already uses -ffunction-sections (if CONFIG_REORDER), so
> > the big question is how usable is ld --gc-sections. Such a feature would
> > be quite important for embedded systems (and for RAM footprint in
> > general) as it would save a significant amount of .text and .data.
>
> A patch to do this was submitted already by Marcelo Tosatti ..
>
> http://lkml.org/lkml/2006/6/4/169

ah, i missed that patch in the June lock validator frenzy. The results
are astounding:

>> vmlinux shrinks from 1090389 to 983933 bytes, or 106k (~= 10%).

Andrew, Linus, Kai, Sam: a must-have feature! This saves more kernel
kernel image RAM than all the other kernel shrinking efforts of the past
2 years combined - at zero cost.

Ingo
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