arch: Remove Itanium (IA-64) architecture

The Itanium architecture is obsolete, and an informal survey [0] reveals
that any residual use of Itanium hardware in production is mostly HP-UX
or OpenVMS based. The use of Linux on Itanium appears to be limited to
enthusiasts that occasionally boot a fresh Linux kernel to see whether
things are still working as intended, and perhaps to churn out some
distro packages that are rarely used in practice.

None of the original companies behind Itanium still produce or support
any hardware or software for the architecture, and it is listed as
'Orphaned' in the MAINTAINERS file, as apparently, none of the engineers
that contributed on behalf of those companies (nor anyone else, for that
matter) have been willing to support or maintain the architecture
upstream or even be responsible for applying the odd fix. The Intel
firmware team removed all IA-64 support from the Tianocore/EDK2
reference implementation of EFI in 2018. (Itanium is the original
architecture for which EFI was developed, and the way Linux supports it
deviates significantly from other architectures.) Some distros, such as
Debian and Gentoo, still maintain [unofficial] ia64 ports, but many have
dropped support years ago.

While the argument is being made [1] that there is a 'for the common
good' angle to being able to build and run existing projects such as the
Grid Community Toolkit [2] on Itanium for interoperability testing, the
fact remains that none of those projects are known to be deployed on
Linux/ia64, and very few people actually have access to such a system in
the first place. Even if there were ways imaginable in which Linux/ia64
could be put to good use today, what matters is whether anyone is
actually doing that, and this does not appear to be the case.

There are no emulators widely available, and so boot testing Itanium is
generally infeasible for ordinary contributors. GCC still supports IA-64
but its compile farm [3] no longer has any IA-64 machines. GLIBC would
like to get rid of IA-64 [4] too because it would permit some overdue
code cleanups. In summary, the benefits to the ecosystem of having IA-64
be part of it are mostly theoretical, whereas the maintenance overhead
of keeping it supported is real.

So let's rip off the band aid, and remove the IA-64 arch code entirely.
This follows the timeline proposed by the Debian/ia64 maintainer [5],
which removes support in a controlled manner, leaving IA-64 in a known
good state in the most recent LTS release. Other projects will follow
once the kernel support is removed.

[0] https://lore.kernel.org/all/CAMj1kXFCMh_578jniKpUtx_j8ByHnt=s7S+yQ+vGbKt9ud7+kQ@mail.gmail.com/
[1] https://lore.kernel.org/all/0075883c-7c51-00f5-2c2d-5119c1820410@web.de/
[2] https://gridcf.org/gct-docs/latest/index.html
[3] https://cfarm.tetaneutral.net/machines/list/
[4] https://lore.kernel.org/all/87bkiilpc4.fsf@mid.deneb.enyo.de/
[5] https://lore.kernel.org/all/ff58a3e76e5102c94bb5946d99187b358def688a.camel@physik.fu-berlin.de/

Acked-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

1 files changed, 0 insertions, 95 deletions

diff --git a/arch/ia64/include/asm/irqflags.h b/arch/ia64/include/asm/irqflags.h
deleted file mode 100644
index 1dc30f12e545..000000000000
--- a/arch/ia64/include/asm/irqflags.h
+++ /dev/null
@@ -1,95 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-/*
- * IRQ flags defines.
- *
- * Copyright (C) 1998-2003 Hewlett-Packard Co
- *	David Mosberger-Tang <davidm@hpl.hp.com>
- * Copyright (C) 1999 Asit Mallick <asit.k.mallick@intel.com>
- * Copyright (C) 1999 Don Dugger <don.dugger@intel.com>
- */
-
-#ifndef _ASM_IA64_IRQFLAGS_H
-#define _ASM_IA64_IRQFLAGS_H
-
-#include <asm/pal.h>
-#include <asm/kregs.h>
-
-#ifdef CONFIG_IA64_DEBUG_IRQ
-extern unsigned long last_cli_ip;
-static inline void arch_maybe_save_ip(unsigned long flags)
-{
-	if (flags & IA64_PSR_I)
-		last_cli_ip = ia64_getreg(_IA64_REG_IP);
-}
-#else
-#define arch_maybe_save_ip(flags) do {} while (0)
-#endif
-
-/*
- * - clearing psr.i is implicitly serialized (visible by next insn)
- * - setting psr.i requires data serialization
- * - we need a stop-bit before reading PSR because we sometimes
- *   write a floating-point register right before reading the PSR
- *   and that writes to PSR.mfl
- */
-
-static inline unsigned long arch_local_save_flags(void)
-{
-	ia64_stop();
-	return ia64_getreg(_IA64_REG_PSR);
-}
-
-static inline unsigned long arch_local_irq_save(void)
-{
-	unsigned long flags = arch_local_save_flags();
-
-	ia64_stop();
-	ia64_rsm(IA64_PSR_I);
-	arch_maybe_save_ip(flags);
-	return flags;
-}
-
-static inline void arch_local_irq_disable(void)
-{
-#ifdef CONFIG_IA64_DEBUG_IRQ
-	arch_local_irq_save();
-#else
-	ia64_stop();
-	ia64_rsm(IA64_PSR_I);
-#endif
-}
-
-static inline void arch_local_irq_enable(void)
-{
-	ia64_stop();
-	ia64_ssm(IA64_PSR_I);
-	ia64_srlz_d();
-}
-
-static inline void arch_local_irq_restore(unsigned long flags)
-{
-#ifdef CONFIG_IA64_DEBUG_IRQ
-	unsigned long old_psr = arch_local_save_flags();
-#endif
-	ia64_intrin_local_irq_restore(flags & IA64_PSR_I);
-	arch_maybe_save_ip(old_psr & ~flags);
-}
-
-static inline bool arch_irqs_disabled_flags(unsigned long flags)
-{
-	return (flags & IA64_PSR_I) == 0;
-}
-
-static inline bool arch_irqs_disabled(void)
-{
-	return arch_irqs_disabled_flags(arch_local_save_flags());
-}
-
-static inline void arch_safe_halt(void)
-{
-	arch_local_irq_enable();
-	ia64_pal_halt_light();	/* PAL_HALT_LIGHT */
-}
-
-
-#endif /* _ASM_IA64_IRQFLAGS_H */