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The Itanium architecture is obsolete, and an informal survey [0] reveals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

2 files changed, 4 insertions, 15 deletions

diff --git a/drivers/firmware/efi/Kconfig b/drivers/firmware/efi/Kconfig
index 231f1c70d1db..cb374b2da9b7 100644
--- a/drivers/firmware/efi/Kconfig
+++ b/drivers/firmware/efi/Kconfig
@@ -4,7 +4,7 @@ menu "EFI (Extensible Firmware Interface) Support"
 
 config EFI_ESRT
 	bool
-	depends on EFI && !IA64
+	depends on EFI
 	default y
 
 config EFI_VARS_PSTORE
@@ -123,7 +123,7 @@ config EFI_BOOTLOADER_CONTROL
 
 config EFI_CAPSULE_LOADER
 	tristate "EFI capsule loader"
-	depends on EFI && !IA64
+	depends on EFI
 	help
 	  This option exposes a loader interface "/dev/efi_capsule_loader" for
 	  users to load EFI capsules. This driver requires working runtime
@@ -224,7 +224,7 @@ config EFI_DISABLE_PCI_DMA
 
 config EFI_EARLYCON
 	def_bool y
-	depends on SERIAL_EARLYCON && !ARM && !IA64
+	depends on SERIAL_EARLYCON && !ARM
 	select FONT_SUPPORT
 	select ARCH_USE_MEMREMAP_PROT
 
diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index 1599f1176842..47ca652f02f6 100644
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -147,7 +147,7 @@ static ssize_t systab_show(struct kobject *kobj,
 	if (efi.smbios != EFI_INVALID_TABLE_ADDR)
 		str += sprintf(str, "SMBIOS=0x%lx\n", efi.smbios);
 
-	if (IS_ENABLED(CONFIG_IA64) || IS_ENABLED(CONFIG_X86))
+	if (IS_ENABLED(CONFIG_X86))
 		str = efi_systab_show_arch(str);
 
 	return str - buf;
@@ -777,7 +777,6 @@ int __init efi_systab_check_header(const efi_table_hdr_t *systab_hdr)
 	return 0;
 }
 
-#ifndef CONFIG_IA64
 static const efi_char16_t *__init map_fw_vendor(unsigned long fw_vendor,
 						size_t size)
 {
@@ -793,10 +792,6 @@ static void __init unmap_fw_vendor(const void *fw_vendor, size_t size)
 {
 	early_memunmap((void *)fw_vendor, size);
 }
-#else
-#define map_fw_vendor(p, s)	__va(p)
-#define unmap_fw_vendor(v, s)
-#endif
 
 void __init efi_systab_report_header(const efi_table_hdr_t *systab_hdr,
 				     unsigned long fw_vendor)
@@ -900,11 +895,6 @@ char * __init efi_md_typeattr_format(char *buf, size_t size,
 }
 
 /*
- * IA64 has a funky EFI memory map that doesn't work the same way as
- * other architectures.
- */
-#ifndef CONFIG_IA64
-/*
  * efi_mem_attributes - lookup memmap attributes for physical address
  * @phys_addr: the physical address to lookup
  *
@@ -951,7 +941,6 @@ int efi_mem_type(unsigned long phys_addr)
 	}
 	return -EINVAL;
 }
-#endif
 
 int efi_status_to_err(efi_status_t status)
 {