Re: [patch 00/2] improve .text size on gcc 4.0 and newer compilers

Ingo Molnar
2005-12-29T07:41:38Z

* Krzysztof Halasa <khc@pm.waw.pl> wrote:

> Ingo Molnar <mingo@elte.hu> writes:
>
> >> gcc version 4.0.2 20051109 (Red Hat 4.0.2-6)
>
> > another thing: i wanted to decrease the size of -Os
> > (CONFIG_CC_OPTIMIZE_FOR_SIZE) kernels, which e.g. Fedora uses too (to
> > keep the icache footprint down).
>
> Remember the above gcc miscompiles the x86-32 kernel with -Os:
>
> https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=173764

i'm not sure what the point is. There was no sudden rush of -Os related
bugs when Fedora switched to it for the kernel, and the 35% code-size
savings were certainly worth it in terms of icache footprint. Yes, -Os
is a major change for how the compiler works, and the kernel is a major
piece of software.

Ingo