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The Itanium architecture is obsolete, and an informal survey [0] reveals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, 163 deletions

diff --git a/arch/ia64/kernel/machine_kexec.c b/arch/ia64/kernel/machine_kexec.c
deleted file mode 100644
index 4db9ca144fa5..000000000000
--- a/arch/ia64/kernel/machine_kexec.c
+++ /dev/null
@@ -1,163 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0-only
-/*
- * arch/ia64/kernel/machine_kexec.c
- *
- * Handle transition of Linux booting another kernel
- * Copyright (C) 2005 Hewlett-Packard Development Comapny, L.P.
- * Copyright (C) 2005 Khalid Aziz <khalid.aziz@hp.com>
- * Copyright (C) 2006 Intel Corp, Zou Nan hai <nanhai.zou@intel.com>
- */
-
-#include <linux/mm.h>
-#include <linux/kexec.h>
-#include <linux/cpu.h>
-#include <linux/irq.h>
-#include <linux/efi.h>
-#include <linux/numa.h>
-#include <linux/mmzone.h>
-
-#include <asm/efi.h>
-#include <asm/numa.h>
-#include <asm/mmu_context.h>
-#include <asm/setup.h>
-#include <asm/delay.h>
-#include <asm/meminit.h>
-#include <asm/processor.h>
-#include <asm/sal.h>
-#include <asm/mca.h>
-
-typedef void (*relocate_new_kernel_t)(
-					unsigned long indirection_page,
-					unsigned long start_address,
-					struct ia64_boot_param *boot_param,
-					unsigned long pal_addr) __noreturn;
-
-struct kimage *ia64_kimage;
-
-struct resource efi_memmap_res = {
-        .name  = "EFI Memory Map",
-        .start = 0,
-        .end   = 0,
-        .flags = IORESOURCE_BUSY | IORESOURCE_MEM
-};
-
-struct resource boot_param_res = {
-        .name  = "Boot parameter",
-        .start = 0,
-        .end   = 0,
-        .flags = IORESOURCE_BUSY | IORESOURCE_MEM
-};
-
-
-/*
- * Do what every setup is needed on image and the
- * reboot code buffer to allow us to avoid allocations
- * later.
- */
-int machine_kexec_prepare(struct kimage *image)
-{
-	void *control_code_buffer;
-	const unsigned long *func;
-
-	func = (unsigned long *)&relocate_new_kernel;
-	/* Pre-load control code buffer to minimize work in kexec path */
-	control_code_buffer = page_address(image->control_code_page);
-	memcpy((void *)control_code_buffer, (const void *)func[0],
-			relocate_new_kernel_size);
-	flush_icache_range((unsigned long)control_code_buffer,
-			(unsigned long)control_code_buffer + relocate_new_kernel_size);
-	ia64_kimage = image;
-
-	return 0;
-}
-
-void machine_kexec_cleanup(struct kimage *image)
-{
-}
-
-/*
- * Do not allocate memory (or fail in any way) in machine_kexec().
- * We are past the point of no return, committed to rebooting now.
- */
-static void ia64_machine_kexec(struct unw_frame_info *info, void *arg)
-{
-	struct kimage *image = arg;
-	relocate_new_kernel_t rnk;
-	void *pal_addr = efi_get_pal_addr();
-	unsigned long code_addr;
-	int ii;
-	u64 fp, gp;
-	ia64_fptr_t *init_handler = (ia64_fptr_t *)ia64_os_init_on_kdump;
-
-	BUG_ON(!image);
-	code_addr = (unsigned long)page_address(image->control_code_page);
-	if (image->type == KEXEC_TYPE_CRASH) {
-		crash_save_this_cpu();
-		current->thread.ksp = (__u64)info->sw - 16;
-
-		/* Register noop init handler */
-		fp = ia64_tpa(init_handler->fp);
-		gp = ia64_tpa(ia64_getreg(_IA64_REG_GP));
-		ia64_sal_set_vectors(SAL_VECTOR_OS_INIT, fp, gp, 0, fp, gp, 0);
-	} else {
-		/* Unregister init handlers of current kernel */
-		ia64_sal_set_vectors(SAL_VECTOR_OS_INIT, 0, 0, 0, 0, 0, 0);
-	}
-
-	/* Unregister mca handler - No more recovery on current kernel */
-	ia64_sal_set_vectors(SAL_VECTOR_OS_MCA, 0, 0, 0, 0, 0, 0);
-
-	/* Interrupts aren't acceptable while we reboot */
-	local_irq_disable();
-
-	/* Mask CMC and Performance Monitor interrupts */
-	ia64_setreg(_IA64_REG_CR_PMV, 1 << 16);
-	ia64_setreg(_IA64_REG_CR_CMCV, 1 << 16);
-
-	/* Mask ITV and Local Redirect Registers */
-	ia64_set_itv(1 << 16);
-	ia64_set_lrr0(1 << 16);
-	ia64_set_lrr1(1 << 16);
-
-	/* terminate possible nested in-service interrupts */
-	for (ii = 0; ii < 16; ii++)
-		ia64_eoi();
-
-	/* unmask TPR and clear any pending interrupts */
-	ia64_setreg(_IA64_REG_CR_TPR, 0);
-	ia64_srlz_d();
-	while (ia64_get_ivr() != IA64_SPURIOUS_INT_VECTOR)
-		ia64_eoi();
-	rnk = (relocate_new_kernel_t)&code_addr;
-	(*rnk)(image->head, image->start, ia64_boot_param,
-		     GRANULEROUNDDOWN((unsigned long) pal_addr));
-	BUG();
-}
-
-void machine_kexec(struct kimage *image)
-{
-	BUG_ON(!image);
-	unw_init_running(ia64_machine_kexec, image);
-	for(;;);
-}
-
-void arch_crash_save_vmcoreinfo(void)
-{
-#if defined(CONFIG_SPARSEMEM)
-	VMCOREINFO_SYMBOL(pgdat_list);
-	VMCOREINFO_LENGTH(pgdat_list, MAX_NUMNODES);
-#endif
-#ifdef CONFIG_NUMA
-	VMCOREINFO_SYMBOL(node_memblk);
-	VMCOREINFO_LENGTH(node_memblk, NR_NODE_MEMBLKS);
-	VMCOREINFO_STRUCT_SIZE(node_memblk_s);
-	VMCOREINFO_OFFSET(node_memblk_s, start_paddr);
-	VMCOREINFO_OFFSET(node_memblk_s, size);
-#endif
-#if CONFIG_PGTABLE_LEVELS == 3
-	VMCOREINFO_CONFIG(PGTABLE_3);
-#elif CONFIG_PGTABLE_LEVELS == 4
-	VMCOREINFO_CONFIG(PGTABLE_4);
-#endif
-}
-