Re: [PATCH v2 10/28] kbuild: lto: fix module versioning

From: Sami Tolvanen
Date: Tue Sep 08 2020 - 14:37:10 EST

On Thu, Sep 03, 2020 at 03:11:54PM -0700, Kees Cook wrote:
> On Thu, Sep 03, 2020 at 01:30:35PM -0700, Sami Tolvanen wrote:
> > With CONFIG_MODVERSIONS, version information is linked into each
> > compilation unit that exports symbols. With LTO, we cannot use this
> > method as all C code is compiled into LLVM bitcode instead. This
> > change collects symbol versions into .symversions files and merges
> > them in where they are all linked into vmlinux.o at
> > the same time.
> >
> > Signed-off-by: Sami Tolvanen <samitolvanen@xxxxxxxxxx>
> The only thought I have here is I wonder if this change could be made
> universally instead of gating on LTO? (i.e. is it noticeably slower to
> do it this way under non-LTO?)

I don't think it's noticeably slower, but keeping the version information
in object files when possible is cleaner, in my opinion.