[PATCH v6 14/25] kbuild: lto: remove duplicate dependencies from .mod files
samitolvanen at google.com
Thu Dec 3 13:47:48 EST 2020
On Thu, Dec 3, 2020 at 10:00 AM Masahiro Yamada <masahiroy at kernel.org> wrote:
> On Thu, Oct 15, 2020 at 7:50 AM Kees Cook <keescook at chromium.org> wrote:
> > On Mon, Oct 12, 2020 at 05:31:52PM -0700, Sami Tolvanen wrote:
> > > With LTO, llvm-nm prints out symbols for each archive member
> > > separately, which results in a lot of duplicate dependencies in the
> > > .mod file when CONFIG_TRIM_UNUSED_SYMS is enabled. When a module
> > > consists of several compilation units, the output can exceed the
> > > default xargs command size limit and split the dependency list to
> > > multiple lines, which results in used symbols getting trimmed.
> > >
> > > This change removes duplicate dependencies, which will reduce the
> > > probability of this happening and makes .mod files smaller and
> > > easier to read.
> > >
> > > Signed-off-by: Sami Tolvanen <samitolvanen at google.com>
> > > Reviewed-by: Kees Cook <keescook at chromium.org>
> > Hi Masahiro,
> > This appears to be a general improvement as well. This looks like it can
> > land without depending on the rest of the series.
> It cannot.
> Adding "sort -u" is pointless without the rest of the series
> since the symbol duplication happens only with Clang LTO.
> This is not a solution.
> "reduce the probability of this happening" well describes it.
> I wrote a different patch.
Great, thanks for looking into this. I'll drop this patch from the next version.
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