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

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Message-ID: <Z8A_wAbpavm3Ydab@gmail.com>
Date: Thu, 27 Feb 2025 11:34:40 +0100
From: Ingo Molnar <mingo@...nel.org>
To: Arnd Bergmann <arnd@...nel.org>
Cc: linux-kernel@...r.kernel.org, x86@...nel.org,
	Arnd Bergmann <arnd@...db.de>, Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andy Shevchenko <andy@...nel.org>,
	Matthew Wilcox <willy@...radead.org>
Subject: Re: [PATCH v3 00/10] x86: 32-bit cleanups


* Arnd Bergmann <arnd@...nel.org> wrote:

> From: Arnd Bergmann <arnd@...db.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(-)

Sweet! I have applied your series to tip:x86/cpu with some minor tweaks 
and a conflict resolution for pending work in x86/mm. Let's see if 
anyone complains about the removal of these obsolete features.

Thanks,

	Ingo