[PATCH v3 00/10] x86: 32-bit cleanups

Arnd Bergmann
2025-02-26T21:37:34Z

From: Arnd Bergmann <arnd@arndb.de>

While looking at 32-bit arm cleanups, I came across some related topics
on x86 and ended up making a series for those as well.

Primarily this is about running 32-bit kernels on 64-bit hardware,
which usually works but should probably be discouraged more clearly by
only providing support for features that are used on real 32-bit hardware:

I found only a few 2003-era high-end servers (HP DL740 and DL760 G2)
that were the only possible remaining uses of HIGHMEM64G and BIGSMP after
the removal of 32-bit NUMA machines in 2014. Similarly, there is only
one generation of hardware with support for VT-x. All these features
can be removed without hurting users.

In the CPU selection, building a 32-bit kernel optimized for AMD K8
or Intel Core2 is anachronistic, so instead only 32-bit CPU types need
to be offered as optimization targets. The "generic" target on 64-bit
turned out to be slightly broken, so I included a fix for that as well.

Changes since v2:

- Add a patch for EISA
- keep PHYS_ADDR_T_64BIT enabled for PAE kernels
- drop the Kconfig.platforms and CONFIG_X86_64_NATIVE patches for now
- improve changelog texts

Changes since v1:

- Don't include patch to drop 32-bit KVM support for now
- Drop patch for 64-bit Silverlake support
- Drop 64-bit ISA level selection, only fix default
- Rework MID patch based on comments
- Add a patch to reorganize platform selection
- Add a patch to add -march=native compilation

Arnd Bergmann (10):
x86/Kconfig: Geode CPU has cmpxchg8b
x86: drop 32-bit "bigsmp" machine support
x86: rework CONFIG_GENERIC_CPU compiler flags
x86: drop configuration options for early 64-bit CPUs
x86: remove HIGHMEM64G support
x86: drop SWIOTLB for PAE
x86: drop support for CONFIG_HIGHPTE
x86: document X86_INTEL_MID as 64-bit-only
x86: remove old STA2x11 support
x86: only allow EISA for 32-bit

Documentation/admin-guide/kdump/kdump.rst | 4 -
.../admin-guide/kernel-parameters.txt | 11 -
Documentation/arch/x86/usb-legacy-support.rst | 11 +-
arch/x86/Kconfig | 156 +++---------
arch/x86/Kconfig.cpu | 97 ++------
arch/x86/Makefile | 16 +-
arch/x86/Makefile_32.cpu | 5 +-
arch/x86/configs/xen.config | 2 -
arch/x86/include/asm/page_32_types.h | 4 +-
arch/x86/include/asm/pgalloc.h | 5 -
arch/x86/include/asm/sta2x11.h | 13 -
arch/x86/include/asm/vermagic.h | 4 -
arch/x86/kernel/apic/Makefile | 3 -
arch/x86/kernel/apic/apic.c | 3 -
arch/x86/kernel/apic/bigsmp_32.c | 105 --------
arch/x86/kernel/apic/local.h | 13 -
arch/x86/kernel/apic/probe_32.c | 29 ---
arch/x86/mm/init_32.c | 9 +-
arch/x86/mm/pgtable.c | 27 +-
arch/x86/pci/Makefile | 2 -
arch/x86/pci/sta2x11-fixup.c | 233 ------------------
drivers/misc/mei/Kconfig | 2 +-
22 files changed, 66 insertions(+), 688 deletions(-)
delete mode 100644 arch/x86/include/asm/sta2x11.h
delete mode 100644 arch/x86/kernel/apic/bigsmp_32.c
delete mode 100644 arch/x86/pci/sta2x11-fixup.c

--
2.39.5

To: x86@kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andy Shevchenko <andy@kernel.org>
Cc: Matthew Wilcox <willy@infradead.org>