Re: [PATCH 0/3] build system: section garbage collection for vmlinux

Daniel Walker
2007-09-05T19:36:55Z

On Wed, 2007-09-05 at 21:31 +0200, Adrian Bunk wrote:
> On Wed, Sep 05, 2007 at 08:14:12PM +0100, Denys Vlasenko wrote:
> > On Wednesday 05 September 2007 19:38, Daniel Walker wrote:
> > > > > You version doesn't work with CONFIG_MODULES right?
> > > >
> > > > It works with CONFIG_MODULES.
> > >
> > > Really? Take a look at this version,
> > >
> > > http://lkml.org/lkml/2006/6/4/169
> > >
> > > Marcello had to implement a two pass build to add back symbol used in
> > > modules which got removed from the main kernel.. You don't appear to do
> > > that. Marcelo also claims better size reduction than you.
> >
> > This will discard EXPORT_SYMBOLs potentially used by
> > out-of-tree modules.
> >
> > I also saw ~10% size reductions, but then at run-time test modules
> > failed to load, they didn't find needed symbols.
> >
> > OTOH if I know that I am not going to be using such modules,
> > then this can be done. Will require another CONFIG_xxx, though.
>
> One point to keep in mind is that the space penalty of CONFIG_MODULES=y
> is so big that CONFIG_MODULES=n is actually the most interesting case
> for small systems that really need small kernels.

Marcelo's version actual deals with the CONFIG_MODULES=y penalty , which
is interesting to me .. It removes symbols added for CONFIG_MODULES
which actually aren't used .. So CONFIG_MODULES=y is just as interesting
as without (to me at least..).

Daniel