linux-kernel - Re: [RFC PATCH 0/5] Retire IA64/Itanium support

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Message-ID: <mhng-5f83e606-a48d-4d18-bae1-20a6cc01952e@palmer-ri-x1c9>
Date:   Wed, 15 Feb 2023 10:20:47 -0800 (PST)
From:   Palmer Dabbelt <palmer@...belt.com>
To:     ardb@...nel.org
CC:     linux-kernel@...r.kernel.org, corbet@....net,
        Arnd Bergmann <arnd@...db.de>, tony.luck@...el.com,
        jrtc27@...c27.com, glaubitz@...sik.fu-berlin.de,
        willy@...radead.org, Marc Zyngier <maz@...nel.org>,
        linux@...ck-us.net, Linus Torvalds <torvalds@...ux-foundation.org>,
        linux-ia64@...r.kernel.org
Subject:     Re: [RFC PATCH 0/5] Retire IA64/Itanium support

On Wed, 15 Feb 2023 09:00:28 PST (-0800), ardb@...nel.org wrote:
> On Wed, 15 Feb 2023 at 17:50, Palmer Dabbelt <palmer@...belt.com> wrote:
>>
>> On Wed, 15 Feb 2023 02:00:03 PST (-0800), ardb@...nel.org wrote:
>> > The IA64 port of Linux has no maintainer, and according to a report from
>> > its only remaining user [0], it has been broken for a month and nobody
>> > cares.
>> >
>> > Given that keeping a complex but unused architecture alive uses up
>> > valuable developer bandwidth, let's just get rid of it.
>> >
>> > This supersedes my patch proposing to mark it as 'dead', which received
>> > no replies from anyone that wants to keep it alive. [1]
>> >
>> > [0] https://www.spinics.net/lists/linux-ia64/msg21926.html
>> > [1] https://lore.kernel.org/all/20230128122904.1345120-1-ardb@kernel.org/
>> >
>> > Cc: Jonathan Corbet <corbet@....net>
>> > Cc: Arnd Bergmann <arnd@...db.de>
>> > Cc: Tony Luck <tony.luck@...el.com>
>> > Cc: Jessica Clarke <jrtc27@...c27.com>
>> > Cc: John Paul Adrian Glaubitz <glaubitz@...sik.fu-berlin.de>
>> > Cc: Matthew Wilcox <willy@...radead.org>
>> > Cc: Marc Zyngier <maz@...nel.org>
>> > Cc: Guenter Roeck <linux@...ck-us.net>
>> > Cc: Linus Torvalds <torvalds@...ux-foundation.org>
>> > Cc: linux-ia64@...r.kernel.org
>> >
>> > Ard Biesheuvel (5):
>> >   arch: Remove Itanium (IA-64) architecture
>> >   kernel: Drop IA64 support from sig_fault handlers
>> >   Documentation: Drop IA64 from feature descriptions
>> >   lib/raid6: Drop IA64 support
>> >   Documentation: Drop or replace remaining mentions of IA64
>>
>> Not sure if I'm missing it in the diff, but it looks like there's also a
>> bunch of "#ifdef __ia64__" and "#ifdef __IA64__" type code spread
>> throughout the kernel.  I didn't look at the actual diff, but it's in
>> files that aren't showing up in the diffstat.
>>
>
> Thanks for taking a look. It seems I indeed missed a couple.
>
>> Just "git grep -i __ia64__" lists a bunch.  I didn't look at all of
>> them, but at least spot checking include/acpi/actypes.h looks like it's
>> a real Itanium workaround.  If the arch goes, it's probbaly worth
>> removing those too?
>>
>
> The ACPI code is synced with another project, so I didn't touch it.
> Same goes for some other header files where IA-64 is referenced, e.g.,
> in the PE/COFF header stuff.

Thanks, I didn't know that.  Pretty sure there's some scattered in 
drivers, but...

>> There's also some mentions of "Itanium" in Documentation outside that
>> don't look like they got caught here.  Not sure if they'd be worth
>> getting rid of, though as they could still be useful examples.  The
>> blurb in Documentation/memory-barriers.txt looks pretty port-specific,
>> though.
>>
>
> Yeah, I don't think it is necessary to rewrite history soviet-style,
> so some remaining references are fine IMHO.

That seems reasonable to me -- assuming the port goes the rest is just 
dead code so it'll filter out over time (presumably all over userspace 
too, which will take a while).