Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
MIME-Version: 1.0
References: <20221018020519.never.337-kees@kernel.org> <CAMj1kXGjF63wK7m8BqC=WX6sA425BTVwQWk9ERN3gG8s==4mjw@mail.gmail.com>
 <8d40dad4-4b20-2ec3-a8e1-706dd415f0d2@igalia.com>
In-Reply-To: <8d40dad4-4b20-2ec3-a8e1-706dd415f0d2@igalia.com>
From:   Ard Biesheuvel <ardb@kernel.org>
Date:   Tue, 18 Oct 2022 16:38:39 +0200
Message-ID: <CAMj1kXF4D8fWV2hNa+R9-c_dLBCo37_qQjB2zBM2DvNG69oCxw@mail.gmail.com>
Subject: Re: [PATCH 0/5] pstore: Use zstd directly by default for compression
To:     "Guilherme G. Piccoli" <gpiccoli@igalia.com>
Cc:     Kees Cook <keescook@chromium.org>, Tony Luck <tony.luck@intel.com>,
        Nick Terrell <terrelln@fb.com>, linux-kernel@vger.kernel.org,
        linux-hardening@vger.kernel.org
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Tue, 18 Oct 2022 at 16:11, Guilherme G. Piccoli <gpiccoli@igalia.com> wrote:
>
> On 18/10/2022 05:20, Ard Biesheuvel wrote:
> > [...]
> > So again, I suggest to simply drop this non-feature, and standardize
> > on either zlib or zstd using the library interface exclusively. If
> > someone present a compelling use case, we can always consider adding
> > it back in some form.
> >
> > As for the choice of algorithm, given the equal performance using the
> > default compression level, and the difference in code size, I don't
> > see why zstd should be preferred here. If anything, it only increases
> > the likelihood of hitting another error if we are panicking due to
> > some memory corruption issue.
>
> I think it's a good argument - would zlib be simpler in code than zstd?

I think it should be rather straight-forward. Note that this is what
we had before 2016 when all the 'features' were starting to get added.

> I've checked the zstd patch from Kees - not complex per se, but would be
> great if we could have a simple mechanism, without the need of the ifdef
> there for example...
>
> Cheers,
>
>
> Guilherme