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

[Palmer Dabbelt]

On Wed, 15 Feb 2023 09:00:28 PST (-0800), ardb@xxxxxxxxxx wrote:
> On Wed, 15 Feb 2023 at 17:50, Palmer Dabbelt <palmer@xxxxxxxxxxx> wrote:
> > On Wed, 15 Feb 2023 02:00:03 PST (-0800), ardb@xxxxxxxxxx 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@xxxxxxxxxx/
> > >
> > > Cc: Jonathan Corbet <corbet@xxxxxxx>
> > > Cc: Arnd Bergmann <arnd@xxxxxxxx>
> > > Cc: Tony Luck <tony.luck@xxxxxxxxx>
> > > Cc: Jessica Clarke <jrtc27@xxxxxxxxxx>
> > > Cc: John Paul Adrian Glaubitz <glaubitz@xxxxxxxxxxxxxxxxxxx>
> > > Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
> > > Cc: Marc Zyngier <maz@xxxxxxxxxx>
> > > Cc: Guenter Roeck <linux@xxxxxxxxxxxx>
> > > Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> > > Cc: linux-ia64@xxxxxxxxxxxxxxx
> > >
> > > 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).