objective rules for architecture removal

[Waldemar Brodkorb <wbx@openadk.org>]

Hi Linus,

are there any objective rules for removal of architecture support from
the Linux kernel tree?

I recognized this week that avr32 support was removed recently.
https://lkml.org/lkml/2017/3/1/694

The major reasons are:
 - end-of-life for hardware
 - no upstream gcc (very old)
 - no users or distribution supporting it
 - shared driver code with ARM architecture

AVR32 has a working distribution (https://openadk.org) and some users.
A year ago Mario Haustein from Technical University Chemnitz submitted some
patches to OpenADK for better AVR32 support. They have approx. 100 devices in use. 
And I donated a NGW100 board to one of the u-boot maintainers to keep u-boot
support solid. 

It is possible to use gcc 4.4.7 with some patches, which was used a long time
in OpenWrt avr32 port:
https://cgit.openadk.org/cgi/cgit/openadk.git/tree/toolchain/gcc/patches/4.4.7

I always loved that Linux kernel does support many architectures and keep supporting
all of them. Any chance to rethink about the removal?

Couldn't be the shared drivers be separated, so that the ARM drivers get there 
new improvements? It is a naive assumption from an embedded Linux hacker
trying to keep uClibc and all it's architecture support alive. 
(https://uclibc-ng.org)

best regards
 Waldemar