Re: [GIT PULL v2] clang-lto for v5.12-rc1

[Alexander Lobakin]

From: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Date: Tue, 23 Feb 2021 12:33:05 -0800

> On Tue, Feb 23, 2021 at 9:49 AM Linus Torvalds
> <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
> >
> > On Mon, Feb 22, 2021 at 3:11 PM Kees Cook <keescook@xxxxxxxxxxxx> wrote:
> > >
> > > While x86 LTO enablement is done[1], it depends on some objtool
> > > clean-ups[2], though it appears those actually have been in linux-next
> > > (via tip/objtool/core), so it's possible that if that tree lands [..]
> >
> > That tree is actually next on my list of things to merge after this
> > one, so it should be out soonish.
>
> "soonish" turned out to be later than I thought, because my "build
> changes" set of pulls included the module change that I then wasted a
> lot of time on trying to figure out why it slowed down my build so
> much.

I guess it's about CONFIG_TRIM_UNUSED_KSYMS you disabled in your tree.
Well, it's actually widely used, mostly in the embedded world where
there are often no out-of-tree modules, but a need to save as much
space as possible.
For full-blown systems and distributions it's almost needless, right.

> But it's out now, as pr-tracker-bot already noted.
>
>               Linus

Thanks,
Al