ia64 removal (was: Re: lockref scalability on x86-64 vs cpu_relax)

[Jessica Clarke]

On Fri, Jan 13, 2023 at 08:55:41AM +0100, Ard Biesheuvel wrote:
> On Fri, 13 Jan 2023 at 01:31, Luck, Tony <tony.luck at intel.com> wrote:
> >
> > > Yeah, if it was ia64-only, it's a non-issue these days. It's dead and
> > > in pure maintenance mode from a kernel perspective (if even that).
> >
> > There's not much "simultaneous" in the SMT on ia64. One thread in a
> > spin loop will hog the core until the h/w switches to the other thread some
> > number of cycles (hundreds, thousands? I really can remember). So I
> > was pretty generous with dropping cpu_relax() into any kind of spin loop.
> >
> > Is it time yet for:
> >
> > $ git rm -r arch/ia64
> >
> 
> Hi Tony,
> 
> Can I take that as an ack on [0]? The EFI subsystem has evolved
> substantially over the years, and there is really no way to do any
> IA64 testing beyond build testing, so from that perspective, dropping
> it entirely would be welcomed.

For what it's worth, Debian and Gentoo both have ia64 ports with active
users (6.1 looks like it currently fails to build in Debian due to a
minor packaging issue, but various versions of 6.0 were built and
published, and one of those is running on the one ia64 Debian builder I
personally have access to).

Jess