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The Itanium architecture is obsolete, and an informal survey [0] reveals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

5 files changed, 3 insertions, 19 deletions

diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index a73246c3c35e..9bcf5641a7cf 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -259,7 +259,7 @@ void acpi_table_print_madt_entry (struct acpi_subtable_header *madt);
 /* the following numa functions are architecture-dependent */
 void acpi_numa_slit_init (struct acpi_table_slit *slit);
 
-#if defined(CONFIG_X86) || defined(CONFIG_IA64) || defined(CONFIG_LOONGARCH)
+#if defined(CONFIG_X86) || defined(CONFIG_LOONGARCH)
 void acpi_numa_processor_affinity_init (struct acpi_srat_cpu_affinity *pa);
 #else
 static inline void
@@ -1114,15 +1114,8 @@ static inline int acpi_get_lps0_constraint(struct device *dev)
 	return ACPI_STATE_UNKNOWN;
 }
 #endif /* CONFIG_SUSPEND && CONFIG_X86 */
-#ifndef CONFIG_IA64
 void arch_reserve_mem_area(acpi_physical_address addr, size_t size);
 #else
-static inline void arch_reserve_mem_area(acpi_physical_address addr,
-					  size_t size)
-{
-}
-#endif /* CONFIG_X86 */
-#else
 #define acpi_os_set_prepare_sleep(func, pm1a_ctrl, pm1b_ctrl) do { } while (0)
 #endif
 
diff --git a/include/linux/efi.h b/include/linux/efi.h
index 80b21d1c6eaf..9cc5bf32f6f2 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -358,13 +358,10 @@ void efi_native_runtime_setup(void);
  * where the UEFI SPEC breaks the line.
  */
 #define NULL_GUID				EFI_GUID(0x00000000, 0x0000, 0x0000,  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00)
-#define MPS_TABLE_GUID				EFI_GUID(0xeb9d2d2f, 0x2d88, 0x11d3,  0x9a, 0x16, 0x00, 0x90, 0x27, 0x3f, 0xc1, 0x4d)
 #define ACPI_TABLE_GUID				EFI_GUID(0xeb9d2d30, 0x2d88, 0x11d3,  0x9a, 0x16, 0x00, 0x90, 0x27, 0x3f, 0xc1, 0x4d)
 #define ACPI_20_TABLE_GUID			EFI_GUID(0x8868e871, 0xe4f1, 0x11d3,  0xbc, 0x22, 0x00, 0x80, 0xc7, 0x3c, 0x88, 0x81)
 #define SMBIOS_TABLE_GUID			EFI_GUID(0xeb9d2d31, 0x2d88, 0x11d3,  0x9a, 0x16, 0x00, 0x90, 0x27, 0x3f, 0xc1, 0x4d)
 #define SMBIOS3_TABLE_GUID			EFI_GUID(0xf2fd1544, 0x9794, 0x4a2c,  0x99, 0x2e, 0xe5, 0xbb, 0xcf, 0x20, 0xe3, 0x94)
-#define SAL_SYSTEM_TABLE_GUID			EFI_GUID(0xeb9d2d32, 0x2d88, 0x11d3,  0x9a, 0x16, 0x00, 0x90, 0x27, 0x3f, 0xc1, 0x4d)
-#define HCDP_TABLE_GUID				EFI_GUID(0xf951938d, 0x620b, 0x42ef,  0x82, 0x79, 0xa8, 0x4b, 0x79, 0x61, 0x78, 0x98)
 #define UGA_IO_PROTOCOL_GUID			EFI_GUID(0x61a4d49e, 0x6f68, 0x4f1b,  0xb9, 0x22, 0xa8, 0x6e, 0xed, 0x0b, 0x07, 0xa2)
 #define EFI_GLOBAL_VARIABLE_GUID		EFI_GUID(0x8be4df61, 0x93ca, 0x11d2,  0xaa, 0x0d, 0x00, 0xe0, 0x98, 0x03, 0x2b, 0x8c)
 #define UV_SYSTEM_TABLE_GUID			EFI_GUID(0x3b13a7d4, 0x633e, 0x11dd,  0x93, 0xec, 0xda, 0x25, 0x56, 0xd8, 0x95, 0x93)
@@ -851,10 +848,6 @@ static inline int efi_range_is_wc(unsigned long start, unsigned long len)
 	return 1;
 }
 
-#ifdef CONFIG_EFI_PCDP
-extern int __init efi_setup_pcdp_console(char *);
-#endif
-
 /*
  * We play games with efi_enabled so that the compiler will, if
  * possible, remove EFI-related code altogether.
diff --git a/include/linux/mm.h b/include/linux/mm.h
index bf5d0b1b16f4..17d530e12f70 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -362,8 +362,6 @@ extern unsigned int kobjsize(const void *objp);
 # define VM_SAO		VM_ARCH_1	/* Strong Access Ordering (powerpc) */
 #elif defined(CONFIG_PARISC)
 # define VM_GROWSUP	VM_ARCH_1
-#elif defined(CONFIG_IA64)
-# define VM_GROWSUP	VM_ARCH_1
 #elif defined(CONFIG_SPARC64)
 # define VM_SPARC_ADI	VM_ARCH_1	/* Uses ADI tag for access control */
 # define VM_ARCH_CLEAR	VM_SPARC_ADI
diff --git a/include/linux/moduleparam.h b/include/linux/moduleparam.h
index 962cd41a2cb5..99e4f1f718c7 100644
--- a/include/linux/moduleparam.h
+++ b/include/linux/moduleparam.h
@@ -276,7 +276,7 @@ struct kparam_array
    read-only sections (which is part of respective UNIX ABI on these
    platforms). So 'const' makes no sense and even causes compile failures
    with some compilers. */
-#if defined(CONFIG_ALPHA) || defined(CONFIG_IA64) || defined(CONFIG_PPC64)
+#if defined(CONFIG_ALPHA) || defined(CONFIG_PPC64)
 #define __moduleparam_const
 #else
 #define __moduleparam_const const
diff --git a/include/trace/events/mmflags.h b/include/trace/events/mmflags.h
index 1478b9dd05fa..d801409b33cf 100644
--- a/include/trace/events/mmflags.h
+++ b/include/trace/events/mmflags.h
@@ -144,7 +144,7 @@ IF_HAVE_PG_ARCH_X(arch_3)
 #define __VM_ARCH_SPECIFIC_1 {VM_PAT,     "pat"           }
 #elif defined(CONFIG_PPC)
 #define __VM_ARCH_SPECIFIC_1 {VM_SAO,     "sao"           }
-#elif defined(CONFIG_PARISC) || defined(CONFIG_IA64)
+#elif defined(CONFIG_PARISC)
 #define __VM_ARCH_SPECIFIC_1 {VM_GROWSUP,	"growsup"	}
 #elif !defined(CONFIG_MMU)
 #define __VM_ARCH_SPECIFIC_1 {VM_MAPPED_COPY,"mappedcopy"	}