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

Jesper Juhl
2005-12-30T09:37:15Z

On 12/30/05, Willy Tarreau <willy@w.ods.org> wrote:
> On Fri, Dec 30, 2005 at 09:33:14AM +0100, Jesper Juhl wrote:
> > On 12/30/05, Willy Tarreau <willy@w.ods.org> wrote:
> >
> > >
> > > Can't we elect a recommended gcc version that distro makers could
> > > ship under the name kgcc as it has been the case for some time,
> > > and try to stick to that version for as long as possible ? The only
> > > real reason to upgrade it would be to support newer archs, while at
> > > the moment, we try to support compilers which are shipped as default
> > > *user-space* compilers.
> > >
> > As I see it, doing that would
> > - put extra work on distributors.
>
> In the short term, yes. In the mid-term, I don't think so. Having one package
> which does not need to change and another one which evolves regardless of
> kernel needs is less work than ensuring that a single package is still
> compatible with everyone's needs. Think about support too : "what gcc version
> did you use ?" would simply become "did you build with kgcc ?"
>
> > - bloat users systems with the need to have two gcc versions installed.
>
> $ size /usr/lib/gcc-lib/i586-pc-linux-gnu/3.3.6/cc1
> text data bss dec hex filename
> 3430228 2680 746688 4179596 3fc68c /usr/lib/gcc-lib/i586-pc-linux-gnu/3.3.6/cc1
>
It's not much, agreed, but if the users regular gcc can build the
kernel it's still unnessesary extra bloat to have two gcc's.
But you are right, the bloat issue is just a minor thing.

> You don't even need libgcc nor c++ to build the kernel. Anyway, it should
> not be an absolute requirement, but the *recommended* and *supported* version.
>
> > - decrease testing with different gcc versions, which sometimes uncover bugs.
>
> gcc testing should not consume kernel developpers' time, but gcc's users.
> How many kernel bugs have finally been attributed to a recent change in gcc ?
> A lot I think. Uncovering bugs in gcc is useful but not the primary goal of
> kernel developpers.
>
That's not what I meant. I meant that building the kernel with
different gcc versions sometimes uncover bugs in the *kernel*. I was
not talking about finding bugs in gcc.

--
Jesper Juhl <jesper.juhl@gmail.com>
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