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The Itanium architecture is obsolete, and an informal survey [0] reveals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, 144 deletions

diff --git a/arch/ia64/uv/Makefile b/arch/ia64/uv/Makefile
deleted file mode 100644
index aa9f91947c49..000000000000
--- a/arch/ia64/uv/Makefile
+++ /dev/null
@@ -1,12 +0,0 @@
-# arch/ia64/uv/Makefile
-#
-# This file is subject to the terms and conditions of the GNU General Public
-# License.  See the file "COPYING" in the main directory of this archive
-# for more details.
-#
-# Copyright (C) 2008 Silicon Graphics, Inc.  All Rights Reserved.
-#
-# Makefile for the sn uv subplatform
-#
-
-obj-y += kernel/
diff --git a/arch/ia64/uv/kernel/Makefile b/arch/ia64/uv/kernel/Makefile
deleted file mode 100644
index 297196578d19..000000000000
--- a/arch/ia64/uv/kernel/Makefile
+++ /dev/null
@@ -1,12 +0,0 @@
-# arch/ia64/uv/kernel/Makefile
-#
-# This file is subject to the terms and conditions of the GNU General Public
-# License.  See the file "COPYING" in the main directory of this archive
-# for more details.
-#
-# Copyright (C) 2008 Silicon Graphics, Inc.  All Rights Reserved.
-#
-
-ccflags-y := -Iarch/ia64/sn/include
-
-obj-y				+= setup.o
diff --git a/arch/ia64/uv/kernel/setup.c b/arch/ia64/uv/kernel/setup.c
deleted file mode 100644
index bb025486d791..000000000000
--- a/arch/ia64/uv/kernel/setup.c
+++ /dev/null
@@ -1,120 +0,0 @@
-/*
- * This file is subject to the terms and conditions of the GNU General Public
- * License.  See the file "COPYING" in the main directory of this archive
- * for more details.
- *
- * SGI UV Core Functions
- *
- * Copyright (C) 2008 Silicon Graphics, Inc. All rights reserved.
- */
-
-#include <linux/acpi.h>
-#include <linux/efi.h>
-#include <linux/module.h>
-#include <linux/percpu.h>
-#include <asm/uv/uv.h>
-#include <asm/uv/uv_mmrs.h>
-#include <asm/uv/uv_hub.h>
-
-bool ia64_is_uv;
-EXPORT_SYMBOL_GPL(ia64_is_uv);
-
-DEFINE_PER_CPU(struct uv_hub_info_s, __uv_hub_info);
-EXPORT_PER_CPU_SYMBOL_GPL(__uv_hub_info);
-
-struct redir_addr {
-	unsigned long redirect;
-	unsigned long alias;
-};
-
-#define DEST_SHIFT UVH_RH_GAM_ALIAS210_REDIRECT_CONFIG_0_MMR_DEST_BASE_SHFT
-
-static __initdata struct redir_addr redir_addrs[] = {
-	{UVH_RH_GAM_ALIAS210_REDIRECT_CONFIG_0_MMR, UVH_SI_ALIAS0_OVERLAY_CONFIG},
-	{UVH_RH_GAM_ALIAS210_REDIRECT_CONFIG_1_MMR, UVH_SI_ALIAS1_OVERLAY_CONFIG},
-	{UVH_RH_GAM_ALIAS210_REDIRECT_CONFIG_2_MMR, UVH_SI_ALIAS2_OVERLAY_CONFIG},
-};
-
-static __init void get_lowmem_redirect(unsigned long *base, unsigned long *size)
-{
-	union uvh_si_alias0_overlay_config_u alias;
-	union uvh_rh_gam_alias210_redirect_config_2_mmr_u redirect;
-	int i;
-
-	for (i = 0; i < ARRAY_SIZE(redir_addrs); i++) {
-		alias.v = uv_read_local_mmr(redir_addrs[i].alias);
-		if (alias.s.base == 0) {
-			*size = (1UL << alias.s.m_alias);
-			redirect.v = uv_read_local_mmr(redir_addrs[i].redirect);
-			*base = (unsigned long)redirect.s.dest_base << DEST_SHIFT;
-			return;
-		}
-	}
-	BUG();
-}
-
-void __init uv_probe_system_type(void)
-{
-	struct acpi_table_rsdp *rsdp;
-	struct acpi_table_xsdt *xsdt;
-
-	if (efi.acpi20 == EFI_INVALID_TABLE_ADDR) {
-		pr_err("ACPI 2.0 RSDP not found.\n");
-		return;
-	}
-
-	rsdp = (struct acpi_table_rsdp *)__va(efi.acpi20);
-	if (strncmp(rsdp->signature, ACPI_SIG_RSDP, sizeof(ACPI_SIG_RSDP) - 1)) {
-		pr_err("ACPI 2.0 RSDP signature incorrect.\n");
-		return;
-	}
-
-	xsdt = (struct acpi_table_xsdt *)__va(rsdp->xsdt_physical_address);
-	if (strncmp(xsdt->header.signature, ACPI_SIG_XSDT,
-			sizeof(ACPI_SIG_XSDT) - 1)) {
-		pr_err("ACPI 2.0 XSDT signature incorrect.\n");
-		return;
-	}
-
-	if (!strcmp(xsdt->header.oem_id, "SGI") &&
-	    !strcmp(xsdt->header.oem_table_id + 4, "UV"))
-		ia64_is_uv = true;
-}
-
-void __init uv_setup(char **cmdline_p)
-{
-	union uvh_si_addr_map_config_u m_n_config;
-	union uvh_node_id_u node_id;
-	unsigned long gnode_upper;
-	int nid, cpu, m_val, n_val;
-	unsigned long mmr_base, lowmem_redir_base, lowmem_redir_size;
-
-	get_lowmem_redirect(&lowmem_redir_base, &lowmem_redir_size);
-	node_id.v = uv_read_local_mmr(UVH_NODE_ID);
-	m_n_config.v = uv_read_local_mmr(UVH_SI_ADDR_MAP_CONFIG);
-	mmr_base = uv_read_local_mmr(UVH_RH_GAM_MMR_OVERLAY_CONFIG_MMR) &
-			~UV_MMR_ENABLE;
-
-	m_val = m_n_config.s.m_skt;
-	n_val = m_n_config.s.n_skt;
-	printk(KERN_DEBUG "UV: global MMR base 0x%lx\n", mmr_base);
-
-	gnode_upper = (((unsigned long)node_id.s.node_id) &
-		       ~((1 << n_val) - 1)) << m_val;
-
-	for_each_present_cpu(cpu) {
-		nid = cpu_to_node(cpu);
-		uv_cpu_hub_info(cpu)->lowmem_remap_base = lowmem_redir_base;
-		uv_cpu_hub_info(cpu)->lowmem_remap_top =
-			lowmem_redir_base + lowmem_redir_size;
-		uv_cpu_hub_info(cpu)->m_val = m_val;
-		uv_cpu_hub_info(cpu)->n_val = n_val;
-		uv_cpu_hub_info(cpu)->pnode_mask = (1 << n_val) -1;
-		uv_cpu_hub_info(cpu)->gpa_mask = (1 << (m_val + n_val)) - 1;
-		uv_cpu_hub_info(cpu)->gnode_upper = gnode_upper;
-		uv_cpu_hub_info(cpu)->global_mmr_base = mmr_base;
-		uv_cpu_hub_info(cpu)->coherency_domain_number = 0;/* ZZZ */
-		printk(KERN_DEBUG "UV cpu %d, nid %d\n", cpu, nid);
-	}
-}
-