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From:   Nick Desaulniers <ndesaulniers@google.com>
Date:   Mon, 31 Oct 2022 11:49:21 -0700
Message-ID: <CAKwvOdkNBM2-pMm+fqzXpMxL5745p0Gzmw_+--P8RSqTk=v+VQ@mail.gmail.com>
Subject: Re: [PATCH] Makefile.debug: support for -gz=zstd
To:     Masahiro Yamada <masahiroy@kernel.org>
Cc:     Nathan Chancellor <nathan@kernel.org>,
        Fangrui Song <maskray@google.com>,
        Sedat Dilek <sedat.dilek@dhl.com>,
        Michal Marek <michal.lkml@markovi.net>,
        Nick Terrell <terrelln@fb.com>, Tom Rix <trix@redhat.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        "Peter Zijlstra (Intel)" <peterz@infradead.org>,
        David Gow <davidgow@google.com>,
        Kees Cook <keescook@chromium.org>,
        Josh Poimboeuf <jpoimboe@kernel.org>,
        Dan Williams <dan.j.williams@intel.com>,
        Miguel Ojeda <ojeda@kernel.org>,
        Isabella Basso <isabbasso@riseup.net>,
        Vlastimil Babka <vbabka@suse.cz>,
        Rasmus Villemoes <linux@rasmusvillemoes.dk>,
        linux-kernel@vger.kernel.org, linux-kbuild@vger.kernel.org,
        llvm@lists.linux.dev, sedat.dilek@gmail.com
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On Mon, Oct 24, 2022 at 10:44 AM Nick Desaulniers
<ndesaulniers@google.com> wrote:
>
> On Sun, Oct 23, 2022 at 8:46 AM Sedat Dilek <sedat.dilek@gmail.com> wrote:
> >
> > On Thu, Oct 20, 2022 at 8:43 PM Nathan Chancellor <nathan@kernel.org> wrote:
> > >
> > > On Thu, Oct 20, 2022 at 10:56:49AM -0700, Nick Desaulniers wrote:
> > > > +config DEBUG_INFO_UNCOMPRESSED
> > > > +     bool "Don't compress debug information"
> > > > +     help
> > > > +       Don't compress debug info sections.
> > > > +
> > > >  config DEBUG_INFO_COMPRESSED
> >
> > Also, I prefer...
> >
> > DEBUG_INFO_COMPRESSED_NONE
> > DEBUG_INFO_COMPRESSED_ZLIB
> > DEBUG_INFO_COMPRESSED_ZSTD
> >
> > Following...
> >
> > $ ld.lld-16 -v
> > Debian LLD 16.0.0 (compatible with GNU linkers)
> >
> > $ ld.lld-16 --help | grep compress-debug-sections
> >  --compress-debug-sections=[none,zlib,zstd]
>
> It's a good suggestion, though I deliberately did not modify the
> identifier used for the existing DEBUG_INFO_COMPRESSED.  No defconfigs
> set DEBUG_INFO_COMPRESSED explicitly, but I think one issue with
> changing the identifier of existing kconfigs is that upon upgrading to
> newer kernel sources, if you run `make oldmodconfig` if you previously
> had DEBUG_INFO_COMPRESSED=y, kconfig doesn't know that that option has
> been renamed to DEBUG_INFO_COMPRESSED_ZLIB so it would be silently
> disabled, and image sizes would increase due to uncompressed debug
> info. That seems developer hostile.
>
> Masahiro, what are your thoughts on how to proceed? Should I change
> the pre-existing Kconfig identifier, or "let sleeping dogs lie?"

Hi Masahiro,
What are your thoughts on the above?

> --
> Thanks,
> ~Nick Desaulniers


-- 
Thanks,
~Nick Desaulniers