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The Itanium architecture is obsolete, and an informal survey [0] reveals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, 46 deletions

diff --git a/arch/ia64/include/asm/kexec.h b/arch/ia64/include/asm/kexec.h
deleted file mode 100644
index 294b1e1ebd2d..000000000000
--- a/arch/ia64/include/asm/kexec.h
+++ /dev/null
@@ -1,46 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-#ifndef _ASM_IA64_KEXEC_H
-#define _ASM_IA64_KEXEC_H
-
-#include <asm/setup.h>
-
-/* Maximum physical address we can use pages from */
-#define KEXEC_SOURCE_MEMORY_LIMIT (-1UL)
-/* Maximum address we can reach in physical address mode */
-#define KEXEC_DESTINATION_MEMORY_LIMIT (-1UL)
-/* Maximum address we can use for the control code buffer */
-#define KEXEC_CONTROL_MEMORY_LIMIT TASK_SIZE
-
-#define KEXEC_CONTROL_PAGE_SIZE (8192 + 8192 + 4096)
-
-/* The native architecture */
-#define KEXEC_ARCH KEXEC_ARCH_IA_64
-
-#define kexec_flush_icache_page(page) do { \
-                unsigned long page_addr = (unsigned long)page_address(page); \
-                flush_icache_range(page_addr, page_addr + PAGE_SIZE); \
-        } while(0)
-
-extern struct kimage *ia64_kimage;
-extern const unsigned int relocate_new_kernel_size;
-extern void relocate_new_kernel(unsigned long, unsigned long,
-		struct ia64_boot_param *, unsigned long);
-static inline void
-crash_setup_regs(struct pt_regs *newregs, struct pt_regs *oldregs)
-{
-}
-extern struct resource efi_memmap_res;
-extern struct resource boot_param_res;
-extern void kdump_smp_send_stop(void);
-extern void kdump_smp_send_init(void);
-extern void kexec_disable_iosapic(void);
-extern void crash_save_this_cpu(void);
-struct rsvd_region;
-extern unsigned long kdump_find_rsvd_region(unsigned long size,
-		struct rsvd_region *rsvd_regions, int n);
-extern void kdump_cpu_freeze(struct unw_frame_info *info, void *arg);
-extern int kdump_status[];
-extern atomic_t kdump_cpu_freezed;
-extern atomic_t kdump_in_progress;
-
-#endif /* _ASM_IA64_KEXEC_H */