Re: [PATCH 4/7] module: avoid code duplication in include/linux/export.h

[Jessica Yu]

+++ Rasmus Villemoes [31/10/19 12:03 +0100]:
> On 31/10/2019 11.13, Jessica Yu wrote:
> > +++ Rasmus Villemoes [29/10/19 22:11 +0100]:
> > > On 29/10/2019 20.19, Jessica Yu wrote:
>
> > > > Apparently ld does not do the deduplication for SHF_MERGE|SHF_STRINGS
> > > > sections for relocatable files (ld -r), which kernel modules are. See:
> > > >
> > > >    https://sourceware.org/ml/binutils/2009-07/msg00291.html
> > >
> > > I know <https://patches-gcc.linaro.org/patch/5858/> :)
> >
> > That is exactly what we need! :)
> >
> > > > But, the strings do get deduplicated for vmlinux. Not sure if we can
> > > > find a workaround for modules or if the benefit is significant enough
> > > > if it only for vmlinux.
> > >
> > > I think it's definitely worth if, even if it "only" benefits vmlinux for
> > > now. And I still hope to revisit the --force-section-merge some day, but
> > > it's very far down my priority list.
> >
> > Yeah, I think it's worth having too.
> >
> > If you don't have any extra cycles at the moment, and it's far down
> > your priority list, do you mind if I take a look and maybe try to push
> > that patch of yours upstream again?
>
> Knock yourself out :) IIRC, it did actually work for the powerpc I was
> targeting, but I don't remember if that was just "readelf/objdump
> inspection of the ELF files looks reasonable" or if I actually tried
> loading the modules. I've pushed the patch to
> https://github.com/Villemoes/binutils-gdb/commit/107b9302858fc5fc1a1690f4a36e1f80808ab421
> so you don't have to copy-paste from a browser.

Thanks a bunch!

> I don't know how successful I'd
> > be, but now since it's especially relevant for namespaces, it's
> > definitely worth looking at again.
>
> Yeah, but even ignoring namespaces, it would be nice to have format
> strings etc. deduplicated. Please keep me cc'ed on any progress you make.

Thanks, I'll keep you posted if I manage to get somewhere with it :)