Re: [GIT pull] perf/urgent for 5.7-rc2

[Linus Torvalds]

On Sun, Apr 19, 2020 at 6:57 AM Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote:
>
> please pull the latest perf/urgent branch from:
>
>    git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git perf-urgent-2020-04-19

So this one took me by surprise, because it only touched the 'tools'
subdirectory for the perf tool, and then when I did what I thought
would be a trivial test build, it re-built the whole kernel.

And that made me go "Whaa?!?"

After looking at it for a while (longer than I really want to admit),
I realized that it's because the headers are also shared with objtool,
and it all kind of made sense.

I say "kind of" because I would have wished that objtool wouldn't
necessarily rebuild everything.

So I'm wondering if there any way that objtool could be run at
link-time (and archive time) rather than force a re-build of all the
object files from source?

This is not a huge deal, it's not like the occasional full rebuild is
_that_ big of a problem, but since I was surprised, I thought I'd
ask..

              Linus