Re: Old platforms: bring out your dead

On Wed, Jan 13, 2021 at 11:31 AM Andy Shevchenko
[off-list ref] wrote:

On Sat, Jan 9, 2021 at 12:58 AM Arnd Bergmann [off-list ref] wrote:

quoted

After v5.10 was officially declared an LTS kernel,

I have a question here. Maybe I have missed something, but how LTS
helps in this case? LTS AFAIR has a rule "upstream first". How can you
provide a patch to be backported if there is no upstream for it
anymore?

Platform specific bugs are usually not the problem here, and if something
does happen on deleted code, I would expect you can get an exception
to the "upstream first" rule.

What I was getting at here were the things in the second category, the
stuff that is is still maintained and working, but so old that it becomes a
burden for maintainers. If a maintainer knows who all the users are
and what they do with their machines, removing the platform from mainline
would be a chance to get everyone to use the same LTS version so they
can get bugfixes to common kernel code for a few more years and
benefit from everyone else testing the same codebase.

quoted

* 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.

We still have Intel Quark available. I run vanilla from time to time
on it due to the presence of peripherals I can't find elsewhere on x86
boards.

While Quark is derived from a i486 pipeline, the kernel treats it as
CONFIG_M586TSC, as it contains fpu, rdtsc, cpuid and cmpxchg8b
instructions but no cmov or mmx. More importantly, you wouldn't find the
vintage i486 peripherals (drivers/ide, drivers/video/fbdev, VLB, ISA,
floppy) but instead have modern stuff like USB, PCIe, and eMMC.

     Arnd

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