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    SubjectRe: Old platforms: bring out your dead
    From: Arnd Bergmann <arnd@kernel.org>
    Date: Fri, 8 Jan 2021 23:55:06 +0100

    > After v5.10 was officially declared an LTS kernel, I had a look around
    > the Arm platforms that look like they have not seen any patches from
    > their maintainers or users that are actually running the hardware for
    > at least five years (2015 or earlier). I made some statistics and lists
    > for my lwn.net article last year [1], so I'd thought I'd share a summary
    > here for discussion about what we should remove. As I found three
    > years ago when I removed several CPU architectures, it makes sense
    > to do this in bulk, to simplify a scripted search for device drivers, header
    > files and Kconfig options that become unused in the process.
    >
    > This is probably a mix of platforms that are completely unused and
    > those that just work, but I have no good way of knowing which one
    > it is. Without hearing back about these, I'd propose removing all of
    > these:
    >
    > * asm9260 -- added in 2014, no notable changes after 2015
    > * axxia -- added in 2014, no notable changes after 2015
    > * bcm/kona -- added in 2013, no notable changes after 2014
    > * digicolor -- added in 2014, no notable changes after 2015
    > * dove -- added in 2009, obsoleted by mach-mvebu in 2015
    > * efm32 -- added in 2011, first Cortex-M, no notable changes after 2013
    > * nspire -- added in 2013, no notable changes after 2015
    > * picoxcell -- added in 2011, already queued for removal
    > * prima2 -- added in 20111, no notable changes since 2015
    > * spear -- added in 2010, no notable changes since 2015
    > * tango -- added in 2015, sporadic changes until 2017, but abandoned
    > * u300 -- added in 2009, no notable changes since 2013
    > * vt8500 -- added in 2010, no notable changes since 2014
    > * zx --added in 2015 for both 32, 2017 for 64 bit, no notable changes
    >
    > If any of the above are not dead yet[2], please let me know,
    > and we'll keep them.
    >
    > Then there are ARM platforms that are old but have still seen some work
    > in the past years. If I hear nothing, these will all stay, but if maintainers
    > may want to drop them anyway, I can help with that:
    >
    > * clps711x -- prehistoric, converted to multiplatform+DT in 2016, no
    > changes since
    > * cns3xxx -- added in 2010, last fixed in 2019, probably no users left
    > * ep93xx -- added in 2006, LinusW still working on it, any users left?
    > * footbridge -- added in prehistory, stable since ~2013, rmk and LinusW have one
    > * gemini -- added in 2009, LinusW still working on it
    > * hisi (hip01/hip05) -- servers added in 2013, replaced with arm64 in 2016
    > * highbank -- added in 2011, no changes after 2015, but Andre still uses it
    > * iop32x -- added in 2006, no notable changes other than my cleanup, but
    > I think there are still users
    > * ixp4xx -- prehistoric, but LinusW and I are still working on it
    > * lpc18xx -- added in 2015, new dts in 2018, but few other changes
    > * lpc32xx -- added in 2010, multiplatform 2019, hardware is EOL
    > * mmp -- added in 2009, DT support is active, but board files might go
    > * moxart -- added in 2013, last Tested-by in 2017
    > * mv78xx0 -- added in 2008, mostly stale but still users
    > (https://github.com/1000001101000/Debian_on_Buffalo)
    > * nomadik -- added in 2009, LinusW keeps fixing it, probably no other users
    > * oxnas -- added in 2016, but already old then, few changes later
    > * pxa -- prehistoric, but a few boards may still have users
    > * rpc -- prehistoric, but I think Russell still uses his machine
    > * sa1100 -- prehistoric, but rmk and LinusW sporadically working in it
    >
    > 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, added back
    > in 2015 but has been mostly stale again since 2016
    > * c6x: Added in 2011, this has seen very few updates since, but
    > Mark still Acks patches when they come. Like most other DSP platforms,
    > 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 code.
    > * sparc/sun4m: A patch for removing 32-bit Sun sparc support (not LEON)
    > is currently under review
    > * powerpc/cell: I'm the maintainer and I promised to send a patch to remove 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
    > * powerpc/amigaone: last updated in 2009
    > * powerpc/maple: last updated in 2011
    > * m68k/{apollo,hp300,sun3,q40} these are all presumably dead and have not
    > seen updates in many years (atari/amiga/mac and coldfire are very much
    > alive)
    > * 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 stable
    > 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 were
    > 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.
    > * 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 most
    > of those machines are of the 64-bit kind. Later MIPS32 such as 4Kc and
    > later are rather different and widely used.

    I still have some devboards with a 32-bit R3000-like CPU :S
    v5.11-rc6 works well on them.

    > * 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.
    > * 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.
    >
    > Arnd
    >
    > [1] https://lwn.net/Articles/838807/
    > [2] https://www.youtube.com/watch?v=Jdf5EXo6I68

    Thanks,
    Al

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