[PATCH] arm64: Kconfig: Make CPU_BIG_ENDIAN depend on BROKEN

[Guenter Roeck]

On 9/25/25 06:01, Will Deacon wrote:
> On Wed, Sep 24, 2025 at 09:09:16AM -0700, Guenter Roeck wrote:
>> On 9/19/25 11:40, Will Deacon wrote:
>>> Big-endian arm64 configurations are vanishingly rare, yet we still claim
>>> to support them in Linux despite very limited testing or visible
>>> interest. Supporting big-endian adds unnecessary burden to reviewers and
>>> contributors which, without any known active users, is hard to justify.
>>> For example, recent work to improve our futex routines and to implement
>>> nested virtualisation support is non-trivially complicated by having to
>>> support both big- and little-endianness.
>>>
>>> Back in 2019 [1], it was claimed that Huawei were using arm64 big-endian
>>> machines in their telecommunication products but I don't know whether
>>> that's still the case and certainly haven't seen any patch contributions
>>> to help support or maintain it.
>>>
>>> Make CPU_BIG_ENDIAN depend on BROKEN as an initial deprecation step
>>> towards its removal.
>>>
>>> Cc: Catalin Marinas <catalin.marinas at arm.com>
>>> Cc: Marc Zyngier <maz at kernel.org>
>>> Cc: Ard Biesheuvel <ardb at kernel.org>
>>> Cc: Arnd Bergmann <arnd at arndb.de>
>>> Cc: Hanjun Guo <guohanjun at huawei.com>
>>> Cc: Jonathan Cameron <Jonathan.Cameron at huawei.com>
>>> Cc: Guenter Roeck <linux at roeck-us.net>
>>> Link: https://lore.kernel.org/linux-arm-kernel/73701e9f-bee1-7ae8-2277-7a3576171cd4@huawei.com/ [1]
>>> Signed-off-by: Will Deacon <will at kernel.org>
>>> ---
>>>
>>> Cc'ing Guenter as a heads-up in case he needs to turn down his testing
>>> to avoid this causing a false regression report.
>>
>> Cool, one more architecture to drop. I wonder if I should drop arm64 big endian testing
>> for all kernel releases. That would simplify my test infrastructure substantially,
>> and it would avoid useless regressions due to bitrot for older kernel releases
>> if no one is using it anyway. Thoughts ?
> 
> It's entirely up to you, but I'd suggest leaving it running until 6.18
> is out and then turning it all off if nobody has chimed in to say
> they're using this stuff.
> 

Makes sense. I'll do that.

Thanks,
Guenter