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The Itanium architecture is obsolete, and an informal survey [0] reveals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, 148 deletions

diff --git a/arch/ia64/lib/ip_fast_csum.S b/arch/ia64/lib/ip_fast_csum.S
deleted file mode 100644
index fcc0b812ce2e..000000000000
--- a/arch/ia64/lib/ip_fast_csum.S
+++ /dev/null
@@ -1,148 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-/*
- * Optmized version of the ip_fast_csum() function
- * Used for calculating IP header checksum
- *
- * Return: 16bit checksum, complemented
- *
- * Inputs:
- *      in0: address of buffer to checksum (char *)
- *      in1: length of the buffer (int)
- *
- * Copyright (C) 2002, 2006 Intel Corp.
- * Copyright (C) 2002, 2006 Ken Chen <kenneth.w.chen@intel.com>
- */
-
-#include <linux/export.h>
-#include <asm/asmmacro.h>
-
-/*
- * Since we know that most likely this function is called with buf aligned
- * on 4-byte boundary and 20 bytes in length, we can execution rather quickly
- * versus calling generic version of do_csum, which has lots of overhead in
- * handling various alignments and sizes.  However, due to lack of constrains
- * put on the function input argument, cases with alignment not on 4-byte or
- * size not equal to 20 bytes will be handled by the generic do_csum function.
- */
-
-#define in0	r32
-#define in1	r33
-#define in2	r34
-#define in3	r35
-#define in4	r36
-#define ret0	r8
-
-GLOBAL_ENTRY(ip_fast_csum)
-	.prologue
-	.body
-	cmp.ne	p6,p7=5,in1	// size other than 20 byte?
-	and	r14=3,in0	// is it aligned on 4-byte?
-	add	r15=4,in0	// second source pointer
-	;;
-	cmp.ne.or.andcm p6,p7=r14,r0
-	;;
-(p7)	ld4	r20=[in0],8
-(p7)	ld4	r21=[r15],8
-(p6)	br.spnt	.generic
-	;;
-	ld4	r22=[in0],8
-	ld4	r23=[r15],8
-	;;
-	ld4	r24=[in0]
-	add	r20=r20,r21
-	add	r22=r22,r23
-	;;
-	add	r20=r20,r22
-	;;
-	add	r20=r20,r24
-	;;
-	shr.u	ret0=r20,16	// now need to add the carry
-	zxt2	r20=r20
-	;;
-	add	r20=ret0,r20
-	;;
-	shr.u	ret0=r20,16	// add carry again
-	zxt2	r20=r20
-	;;
-	add	r20=ret0,r20
-	;;
-	shr.u	ret0=r20,16
-	zxt2	r20=r20
-	;;
-	add	r20=ret0,r20
-	mov	r9=0xffff
-	;;
-	andcm	ret0=r9,r20
-	.restore sp		// reset frame state
-	br.ret.sptk.many b0
-	;;
-
-.generic:
-	.prologue
-	.save ar.pfs, r35
-	alloc	r35=ar.pfs,2,2,2,0
-	.save rp, r34
-	mov	r34=b0
-	.body
-	dep.z	out1=in1,2,30
-	mov	out0=in0
-	;;
-	br.call.sptk.many b0=do_csum
-	;;
-	andcm	ret0=-1,ret0
-	mov	ar.pfs=r35
-	mov	b0=r34
-	br.ret.sptk.many b0
-END(ip_fast_csum)
-EXPORT_SYMBOL(ip_fast_csum)
-
-GLOBAL_ENTRY(csum_ipv6_magic)
-	ld4	r20=[in0],4
-	ld4	r21=[in1],4
-	zxt4	in2=in2
-	;;
-	ld4	r22=[in0],4
-	ld4	r23=[in1],4
-	dep	r15=in3,in2,32,16
-	;;
-	ld4	r24=[in0],4
-	ld4	r25=[in1],4
-	mux1	r15=r15,@rev
-	add	r16=r20,r21
-	add	r17=r22,r23
-	zxt4	in4=in4
-	;;
-	ld4	r26=[in0],4
-	ld4	r27=[in1],4
-	shr.u	r15=r15,16
-	add	r18=r24,r25
-	add	r8=r16,r17
-	;;
-	add	r19=r26,r27
-	add	r8=r8,r18
-	;;
-	add	r8=r8,r19
-	add	r15=r15,in4
-	;;
-	add	r8=r8,r15
-	;;
-	shr.u	r10=r8,32	// now fold sum into short
-	zxt4	r11=r8
-	;;
-	add	r8=r10,r11
-	;;
-	shr.u	r10=r8,16	// yeah, keep it rolling
-	zxt2	r11=r8
-	;;
-	add	r8=r10,r11
-	;;
-	shr.u	r10=r8,16	// three times lucky
-	zxt2	r11=r8
-	;;
-	add	r8=r10,r11
-	mov	r9=0xffff
-	;;
-	andcm	r8=r9,r8
-	br.ret.sptk.many b0
-END(csum_ipv6_magic)
-EXPORT_SYMBOL(csum_ipv6_magic)