The Itanium architecture is obsolete, and an informal survey [0] reveals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

I added $(srctree)/ to some included Makefiles in the following commits:

 - 3204a7fb98a3 ("kbuild: prefix $(srctree)/ to some included Makefiles")
 - d82856395505 ("kbuild: do not require sub-make for separate output tree builds")

They were a preparation for removing --include-dir flag.

I have never thought --include-dir useful. Rather, it _is_ harmful.

For example, run the following commands:

  $ make -s ARCH=x86 mrproper defconfig
  $ make ARCH=arm O=foo dtbs
  make[1]: Entering directory '/tmp/linux/foo'
    HOSTCC  scripts/basic/fixdep
  Error: kernelrelease not valid - run 'make prepare' to update it
    UPD     include/config/kernel.release
  make[1]: Leaving directory '/tmp/linux/foo'

The first command configures the source tree for x86. The next command
tries to build ARM device trees in the separate foo/ directory - this
must stop because the directory foo/ has not been configured yet.

However, due to --include-dir=$(abs_srctree), the top Makefile includes
the wrong include/config/auto.conf from the source tree and continues
building. Kbuild traverses the directory tree, but of course it does
not work correctly. The Error message is also pointless - 'make prepare'
does not help at all for fixing the issue.

This commit fixes more arch Makefile, and finally removes --include-dir
from the top Makefile.

There are more breakages under drivers/, but I do not volunteer to fix
them all. I just moved --include-dir to drivers/Makefile.

With this commit, the second command will stop with a sensible message.

  $ make -s ARCH=x86 mrproper defconfig
  $ make ARCH=arm O=foo dtbs
  make[1]: Entering directory '/tmp/linux/foo'
    SYNC    include/config/auto.conf.cmd
  ***
  *** The source tree is not clean, please run 'make ARCH=arm mrproper'
  *** in /tmp/linux
  ***
  make[2]: *** [../Makefile:646: outputmakefile] Error 1
  /tmp/linux/Makefile:770: include/config/auto.conf.cmd: No such file or directory
  make[1]: *** [/tmp/linux/Makefile:793: include/config/auto.conf.cmd] Error 2
  make[1]: Leaving directory '/tmp/linux/foo'
  make: *** [Makefile:226: __sub-make] Error 2

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

CONFIG_IA64_ESI is a bool option. I do not know why the Makefile was
written like this, but this should not have any functional change.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>

The objects placed at the head of vmlinux need special treatments:

 - arch/$(SRCARCH)/Makefile adds them to head-y in order to place
   them before other archives in the linker command line.

 - arch/$(SRCARCH)/kernel/Makefile adds them to extra-y instead of
   obj-y to avoid them going into built-in.a.

This commit gets rid of the latter.

Create vmlinux.a to collect all the objects that are unconditionally
linked to vmlinux. The objects listed in head-y are moved to the head
of vmlinux.a by using 'ar m'.

With this, arch/$(SRCARCH)/kernel/Makefile can consistently use obj-y
for builtin objects.

There is no *.o that is directly linked to vmlinux. Drop unneeded code
in scripts/clang-tools/gen_compile_commands.py.

$(AR) mPi needs 'T' to workaround the llvm-ar bug. The fix was suggested
by Nathan Chancellor [1].

[1]: https://lore.kernel.org/llvm/YyjjT5gQ2hGMH0ni@dev-arch.thelio-3990X/

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>

DISCONTIGMEM was marked BROKEN in 5.11. Let's remove it.

Booted SPARSEMEM successfully on rx3600.

Link: https://lkml.kernel.org/r/20210404193440.2615358-1-slyfox@gentoo.org
Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Randy reports the following warning when building ARCH=ia64 with
CONFIG_IA64_PALINFO=m:

../scripts/Makefile.build:68: 'arch/ia64/kernel/palinfo.ko' will not be built even though obj-m is specified.
../scripts/Makefile.build:69: You cannot use subdir-y/m to visit a module Makefile. Use obj-y/m instead.

This message is actually false-positive, and you can get palinfo.ko
correctly built. It is emitted in the archprepare stage, where Kbuild
descends into arch/ia64/kernel to generate include/generated/nr-irqs.h
instead of any kind of kernel objects.

arch/ia64/kernel/nr-irqs.c was introduced by commit 213060a4d699
("[IA64] pvops: paravirtualize NR_IRQS") to pre-calculate:

   NR_IRQS = max(IA64_NATIVE_NR_IRQS, XEN_NR_IRQS, FOO_NR_IRQS...)

Since commit d52eefb47d4e ("ia64/xen: Remove Xen support for ia64"), this
union contains just one field, making NR_IRQS and IA64_NATIVE_NR_IRQS
always match.

So, the following hard-coding now works:

  #define NR_IRQS                IA64_NATIVE_NR_IRQS

If you need to re-introduce NR_IRQS = max(...) gimmick in the future,
please try to implement it in asm-offsets.c instead of a separate file.
It will be possible because the header inclusion has been consolidated
to make asm-offsets.c independent of <asm/irqs.h>.

Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
Tested-by: Randy Dunlap <rdunlap@infradead.org>

Fix linkage error when CONFIG_BINFMT_ELF is selected but CONFIG_COREDUMP
is not:

    ia64-linux-ld: arch/ia64/kernel/elfcore.o: in function `elf_core_write_extra_phdrs':
    elfcore.c:(.text+0x172): undefined reference to `dump_emit'
    ia64-linux-ld: arch/ia64/kernel/elfcore.o: in function `elf_core_write_extra_data':
    elfcore.c:(.text+0x2b2): undefined reference to `dump_emit'

Fixes: 1fcccbac89f5 ("elf coredump: replace ELF_CORE_EXTRA_* macros by functions")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: <stable@vger.kernel.org>
Link: https://lkml.kernel.org/r/20200819064146.12529-1-krzk@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

perfmon has been marked broken and thus been disabled for all builds
for more than two years.  Remove it entirely.

Cc: Anant Thazhemadam <anant.thazhemadam@gmail.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Enthusiastically-ACKed-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Link: https://lore.kernel.org/r/20200911094920.1173631-1-hch@lst.de

The only thing remaining of the machvecs is a few checks if we are
running on an SGI UV system.  Replace those with the existing
is_uv_system() check that has been rewritten to simply check the
OEM ID directly.

That leaves us with a generic kernel that is as fast as the previous
DIG/ZX1/UV kernels, but can support all hardware.  Support for UV
and the HP SBA IOMMU is now optional based on new config options.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lkml.kernel.org/r/20190813072514.23299-27-hch@lst.de
Signed-off-by: Tony Luck <tony.luck@intel.com>

Now that hpsim support is gone, CONFIG_ACPI is forced on for ia64, and
we can remove a few ifdefs for it.

Acked-by: Tom Vaden <tom.vaden@hpe.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lkml.kernel.org/r/20190813072514.23299-20-hch@lst.de
Signed-off-by: Tony Luck <tony.luck@intel.com>