Date: Sun, 17 Dec 2017 20:41:22 +0100
From: Lukasz Majewski <lukma@denx.de>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Alexander Sverdlin <alexander.sverdlin@gmail.com>,
        Linus Walleij <linus.walleij@linaro.org>,
        Hartley Sweeten <hsweeten@visionengravers.com>,
        Russell King <linux@armlinux.org.uk>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Olof Johansson <olof@lixom.net>
Subject: Re: [PATCH v5 0/4] ARM: ep93xx: ts72xx: Add support for BK3 board
Message-ID: <20171217204122.0a10a5e1@jawa>
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Hi Arnd,

> On Wed, Dec 13, 2017 at 9:26 AM, Alexander Sverdlin
> <alexander.sverdlin@gmail.com> wrote:
> > On Wed Dec 13 08:34:22 2017 Linus Walleij
> > <linus.walleij@linaro.org> wrote: =20
> >> Arnd has been nudging me to do DT conversion for EP93xx
> >> so if there are many active industrial users of these
> >> I should prioritize it, because these things have 20+ years
> >> support cycles. =20
> >
> > I'm not sure how important or necessary at all is to change
> > anything in these legacy platforms. =20
>=20
> I suspect that at several points in the next 5 to 10 years, we will
> remove additional platforms or CPU types, as we tend to do when a
> platform becomes a maintenance burden and is clearly not used by
> anyone.

I suppose that at least the last argument is not the case here :-).

>=20
> It's hard to predict in advance what triggers the removal, but as the
> number of platforms that are not using DT or ARCH_MULTIPLATFORM
> goes down to a small number, there will be increased interested in
> either removing or converting the remaining ones. This is not an
> immediate danger at the moment, since we still have 14 platforms that
> are not using ARCH_MULTIPLATFORM, and 23 that have remaining
> board files, but you don't want to be the last user of the last
> platform after the other ones are done ;-)

:-)

>=20
> >> We also need to think about upholding support in GCC for
> >> ARMv4(t) for the foreseeable future if there is a big web of
> >> random deeply embedded systems out there that will need
> >> updates. =20
> >
> > But we should definitely preserve at least what we have. =20
>=20
> Plain ARMv4 (and earlier) support in gcc is already marked
> 'deprecated' and will likely be gone in gcc-8 (it's still there as of
> last week). ARMv4T is going to be around for a while, and you can
> even keep building for ARMv4 using "-march=3Darmv4t -marm" when linking
> with 'ld --fix-v4bx'.

I think that we shall start complaining on the gcc-devel mailing list
now.

I would be hard to wake up in 2 years time and realise that we don't
have a modern compiler.

>=20
> Debian recently did a survey to find out whether there were still
> users on ARMv4 or ARMv4T, and the result was that probably everyone is
> on ARMv5E or ARMv6 for the ARM port (which is separate from the
> ARMHF port that is ARMv7+). See also
> https://lists.debian.org/debian-user/2017/11/msg00379.html
> and let them know quickly if you use Debian stable releases and
> plan to update to Debian 10 (Buster) in the future.
>=20
>      Arnd


Best regards,

Lukasz Majewski

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