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The Itanium architecture is obsolete, and an informal survey [0] reveals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, 66 deletions

diff --git a/arch/ia64/include/asm/pci.h b/arch/ia64/include/asm/pci.h
deleted file mode 100644
index fa8f545c24c9..000000000000
--- a/arch/ia64/include/asm/pci.h
+++ /dev/null
@@ -1,66 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-#ifndef _ASM_IA64_PCI_H
-#define _ASM_IA64_PCI_H
-
-#include <linux/mm.h>
-#include <linux/slab.h>
-#include <linux/spinlock.h>
-#include <linux/string.h>
-#include <linux/types.h>
-#include <linux/scatterlist.h>
-
-#include <asm/io.h>
-#include <asm/hw_irq.h>
-
-struct pci_vector_struct {
-	__u16 segment;	/* PCI Segment number */
-	__u16 bus;	/* PCI Bus number */
-	__u32 pci_id;	/* ACPI split 16 bits device, 16 bits function (see section 6.1.1) */
-	__u8 pin;	/* PCI PIN (0 = A, 1 = B, 2 = C, 3 = D) */
-	__u32 irq;	/* IRQ assigned */
-};
-
-/*
- * Can be used to override the logic in pci_scan_bus for skipping already-configured bus
- * numbers - to be used for buggy BIOSes or architectures with incomplete PCI setup by the
- * loader.
- */
-#define pcibios_assign_all_busses()     0
-
-#define PCIBIOS_MIN_IO		0x1000
-#define PCIBIOS_MIN_MEM		0x10000000
-
-#define HAVE_PCI_MMAP
-#define ARCH_GENERIC_PCI_MMAP_RESOURCE
-#define arch_can_pci_mmap_wc()	1
-
-#define HAVE_PCI_LEGACY
-extern int pci_mmap_legacy_page_range(struct pci_bus *bus,
-				      struct vm_area_struct *vma,
-				      enum pci_mmap_state mmap_state);
-
-char *pci_get_legacy_mem(struct pci_bus *bus);
-int pci_legacy_read(struct pci_bus *bus, u16 port, u32 *val, u8 size);
-int pci_legacy_write(struct pci_bus *bus, u16 port, u32 val, u8 size);
-
-struct pci_controller {
-	struct acpi_device *companion;
-	void *iommu;
-	int segment;
-	int node;		/* nearest node with memory or NUMA_NO_NODE for global allocation */
-
-	void *platform_data;
-};
-
-
-#define PCI_CONTROLLER(busdev) ((struct pci_controller *) busdev->sysdata)
-#define pci_domain_nr(busdev)    (PCI_CONTROLLER(busdev)->segment)
-
-extern struct pci_ops pci_root_ops;
-
-static inline int pci_proc_domain(struct pci_bus *bus)
-{
-	return (pci_domain_nr(bus) != 0);
-}
-
-#endif /* _ASM_IA64_PCI_H */