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Subject: Re: Old platforms: bring out your dead
To:     John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>,
        Arnd Bergmann <arnd@arndb.de>
Cc:     Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-m68k <linux-m68k@lists.linux-m68k.org>,
        Sparc kernel list <sparclinux@vger.kernel.org>,
        Linux-sh list <linux-sh@vger.kernel.org>
References: <ef1dc21f-694b-2433-e1c6-aa121320173e@physik.fu-berlin.de>
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Date:   Mon, 11 Jan 2021 16:04:11 +0100
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Am 10.01.21 um 18:35 schrieb John Paul Adrian Glaubitz:
> Hi Arnd!
>
> (Please let's have this cross-posted for more visibility. I only learned=
 about this
>  while reading Phoronix news)
Same for me!

>> I also looked at non-ARM platforms while preparing for my article. Some=
 of
>> these look like they are no longer actively maintained or used, but I'm=
 not
>> doing anything about those unless the maintainers would like me to:
>>
>> * h8300: Steven Rostedt has repeatedly asked about it to be removed
>>    or fixed in 2020 with no reply. This was killed before in 2013, adde=
d back
>>    in 2015 but has been mostly stale again since 2016
>
> As far as I know, Yoshinori Sato is actively maintaining H8300 support, =
see:
>
>> https://osdn.net/projects/uclinux-h8/
>
>> * c6x: Added in 2011, this has seen very few updates since, but
>>     Mark still Acks patches when they come. Like most other DSP platfor=
ms,
>>     the model of running Linux on a DSP appears to have been obsoleted
>>     by using Linux on ARM with on-chip DSP cores running bare-metal cod=
e.
>> * sparc/sun4m: A patch for removing 32-bit Sun sparc support (not LEON)
>>    is currently under review
>
> I don't think this has reached any agreement yet. Multiple people want i=
t to stay.
>
>> * powerpc/cell: I'm the maintainer and I promised to send a patch to re=
move it.
>>    it's in my backlog but I will get to it. This is separate from PS3,
>>    which is actively maintained and used; spufs will move to ps3
>> * powerpc/chrp (32-bit rs6000, pegasos2): last updated in 2009
>
> I'm still using this. Please keep it.
I can also confirm that Pegasos2 users in the Amiga scene are running Linu=
x
(Debian) on these machines.

>> * powerpc/amigaone: last updated in 2009
I still have 2 of the 3 types of the first generation AmigaOne machines (n=
ot
to be confused with the newer AmigaOne X1000 and X5000 machines based on
PASemi and P5020 CPUs) working here. A third machine needs a repair of the
G4 CPU module (replacement parts already available).
I have to admit however that I yet have to setup an environment that allow=
s
me to regularly test new Linux kernel versions on these machines. Especial=
ly
because there are not many Linux users for these machines - which is likel=
y
due to the fact that no distribution officially supports these machines ou=
t
of the box (the Pegasos2 platform had more luck here). Inputs on how to
automate tests would therefore be very welcome!
Given however that the Debian PowerPC port has a proper maintainer again
(kudos to Adrian!) and there is also another new PowerPC distro (Void Linu=
x),
I would like to ask for a period of grace. After all this is just a hobby
project for me, so keeping up with the pace of the Linux development isn't
always that easy (and no, work on this did not stop in 2009, but shifted m=
ore
towards distro support since then).

>> * powerpc/maple: last updated in 2011
>> * m68k/{apollo,hp300,sun3,q40} these are all presumably dead and have n=
ot
>>    seen updates in many years (atari/amiga/mac and coldfire are very mu=
ch
>>    alive)
>
> Dito. I have both sun3 and hp300 machines.
>
>> * mips/jazz: last updated in 2007
>> * mips/cobalt: last updated in 2010
>>
>> There might be some value in dropping old CPU support on architectures
>> and platforms that are almost exclusively used with more modern CPUs.
>> If there are only few users, those can still keep using v5.10 or v5.4 s=
table
>> kernels for a few more years. Again, I'm not doing anything about them,
>> except mention them since I did the research.
>> These are the oldest one by architecture, and they may have reached
>> their best-served-by-date:
>>
>> * 80486SX/DX: 80386 CPUs were dropped in 2012, and there are
>>   indications that 486 have no users either on recent kernels.
>>   There is still the Vortex86 family of SoCs, and the oldest of those w=
ere
>>   486SX-class, but all the modern ones are 586-class.
>> * Alpha 2106x: First generation that lacks some of the later features.
>>   Since all Alphas are ancient by now, it's hard to tell whether these =
have
>>   any fewer users.
>
> I don't see the point in crippling Alpha support. Does this achieve anyt=
hing?
>
>> * IA64 Merced: first generation Itanium (2001) was quickly replaced by
>>   Itanium II in 2002.
>> * MIPS R3000/TX39xx: 32-bit MIPS-II generation, mostly superseded by
>>   64-bit MIPS-III (R4000 and higher) starting in 1991. arch/mips still
>>   supports these in DECstation and Toshiba Txx9, but it appears that mo=
st
>>   of those machines are of the 64-bit kind. Later MIPS32 such as 4Kc an=
d
>>   later are rather different and widely used.
>> * PowerPC 601 (from 1992) just got removed, later 60x, 4xx, 8xx etc
>>   are apparently all still used.
>> * SuperH SH-2: We discussed removing SH-2 (not J2 or SH-4)
>>   support in the past, I don't think there were any objections, but
>>   nobody submitted a patch.
>
> Isn't SH-2 basically J-2? I'm not sure what we would gain here.
>
>> * 68000/68328 (Dragonball): these are less capable than the
>>   68020+ or the Coldfire MCF5xxx line and similar to the 68360
>>   that was removed in 2016.
>
> Adrian
>