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

Willy Tarreau
2005-12-30T09:41:15Z

On Fri, Dec 30, 2005 at 10:37:08AM +0100, Jesper Juhl wrote:
> 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.

OK. But there will always be people trying to build kernels with any gcc so
I don't think we would lose this bug report channel anyway.

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

Willy