linux-kernel - Re: [PATCH 3/3] arm64: configs: unset CPU_BIG

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Message-ID: <20191014162028.eixypo7vlsb3pdgn@willie-the-truck>
Date:   Mon, 14 Oct 2019 17:20:29 +0100
From:   Will Deacon <will@...nel.org>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Hanjun Guo <guohanjun@...wei.com>,
        Anders Roxell <anders.roxell@...aro.org>,
        Catalin Marinas <catalin.marinas@....com>,
        John Garry <john.garry@...wei.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Olof Johansson <olof@...om.net>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH 3/3] arm64: configs: unset CPU_BIG_ENDIAN

On Sat, Oct 12, 2019 at 04:05:57PM +0200, Arnd Bergmann wrote:
> On Sat, Oct 12, 2019 at 9:33 AM Hanjun Guo <guohanjun@...wei.com> wrote:
> >
> > On 2019/10/11 18:27, Will Deacon wrote:
> > [...]
> > >
> > > Does anybody use BIG_ENDIAN? If we're not even building it then maybe we
> > > should get rid of it altogether on arm64. I don't know of any supported
> > > userspace that supports it or any CPUs that are unable to run little-endian
> > > binaries.
> >
> > FWIW, massive telecommunication products (based on ARM64) form Huawei are using
> > BIG_ENDIAN, and will use BIG_ENDIAN in the near future as well.
> 
> Ok, thanks for the information -- that definitely makes it clear that
> it cannot go
> away anytime soon (though it doesn't stop us from change the
> allmodconfig default
> if we decide that's a good idea).

Agreed on both counts.

> Do you know if there are currently any patches against mainline to
> make big-endian
> work in products, or is everything working out of the box?

I suspect "everything" is probably much narrower in scope than for
little-endian configurations simply because of the lack of distribution
support and associated testing. If the companies using it are willing
to contribute back fixes as they run into problems, then that's probably
the best we can hope for.

Will