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The Itanium architecture is obsolete, and an informal survey [0] reveals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>

3 files changed, 0 insertions, 75 deletions

diff --git a/tools/arch/ia64/include/asm/barrier.h b/tools/arch/ia64/include/asm/barrier.h
deleted file mode 100644
index 6fffe5682713..000000000000
--- a/tools/arch/ia64/include/asm/barrier.h
+++ /dev/null
@@ -1,59 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-/*
- * Copied from the kernel sources to tools/:
- *
- * Memory barrier definitions.  This is based on information published
- * in the Processor Abstraction Layer and the System Abstraction Layer
- * manual.
- *
- * 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 _TOOLS_LINUX_ASM_IA64_BARRIER_H
-#define _TOOLS_LINUX_ASM_IA64_BARRIER_H
-
-#include <linux/compiler.h>
-
-/*
- * Macros to force memory ordering.  In these descriptions, "previous"
- * and "subsequent" refer to program order; "visible" means that all
- * architecturally visible effects of a memory access have occurred
- * (at a minimum, this means the memory has been read or written).
- *
- *   wmb():	Guarantees that all preceding stores to memory-
- *		like regions are visible before any subsequent
- *		stores and that all following stores will be
- *		visible only after all previous stores.
- *   rmb():	Like wmb(), but for reads.
- *   mb():	wmb()/rmb() combo, i.e., all previous memory
- *		accesses are visible before all subsequent
- *		accesses and vice versa.  This is also known as
- *		a "fence."
- *
- * Note: "mb()" and its variants cannot be used as a fence to order
- * accesses to memory mapped I/O registers.  For that, mf.a needs to
- * be used.  However, we don't want to always use mf.a because (a)
- * it's (presumably) much slower than mf and (b) mf.a is supported for
- * sequential memory pages only.
- */
-
-#define mb()		ia64_mf()
-#define rmb()		mb()
-#define wmb()		mb()
-
-#define smp_store_release(p, v)			\
-do {						\
-	barrier();				\
-	WRITE_ONCE(*p, v);			\
-} while (0)
-
-#define smp_load_acquire(p)			\
-({						\
-	typeof(*p) ___p1 = READ_ONCE(*p);	\
-	barrier();				\
-	___p1;					\
-})
-
-#endif /* _TOOLS_LINUX_ASM_IA64_BARRIER_H */
diff --git a/tools/arch/ia64/include/uapi/asm/bitsperlong.h b/tools/arch/ia64/include/uapi/asm/bitsperlong.h
deleted file mode 100644
index 1146d55563db..000000000000
--- a/tools/arch/ia64/include/uapi/asm/bitsperlong.h
+++ /dev/null
@@ -1,9 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
-#ifndef __ASM_IA64_BITSPERLONG_H
-#define __ASM_IA64_BITSPERLONG_H
-
-#define __BITS_PER_LONG 64
-
-#include <asm-generic/bitsperlong.h>
-
-#endif /* __ASM_IA64_BITSPERLONG_H */
diff --git a/tools/arch/ia64/include/uapi/asm/mman.h b/tools/arch/ia64/include/uapi/asm/mman.h
deleted file mode 100644
index 2a19bb1db4ab..000000000000
--- a/tools/arch/ia64/include/uapi/asm/mman.h
+++ /dev/null
@@ -1,7 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
-#ifndef TOOLS_ARCH_IA64_UAPI_ASM_MMAN_FIX_H
-#define TOOLS_ARCH_IA64_UAPI_ASM_MMAN_FIX_H
-#include <uapi/asm-generic/mman.h>
-/* MAP_32BIT is undefined on ia64, fix it for perf */
-#define MAP_32BIT	0
-#endif