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Date: Tue, 8 Sep 2020 11:23:08 -0700
From: Sami Tolvanen <>
To: Kees Cook <>
Cc: Masahiro Yamada <>, Will Deacon <>,
	Peter Zijlstra <>,
	Steven Rostedt <>,
	Greg Kroah-Hartman <>,
	"Paul E. McKenney" <>,
	Nick Desaulniers <>,,,,,,,,
Subject: Re: [PATCH v2 10/28] kbuild: lto: fix module versioning

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 <>
> 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.


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