x86/cpu: Drop configuration options for early 64-bit CPUs

The x86 CPU selection menu is confusing for a number of reasons:

When configuring 32-bit kernels, it shows a small number of early 64-bit
microarchitectures (K8, Core 2) but not the regular generic 64-bit target
that is the normal default.  There is no longer a reason to run 32-bit
kernels on production 64-bit systems, so only actual 32-bit CPUs need
to be shown here.

When configuring 64-bit kernels, the options also pointless as there is
no way to pick any CPU from the past 15 years, leaving GENERIC_CPU as
the only sensible choice.

Address both of the above by removing the obsolete options and making
all 64-bit kernels run on both Intel and AMD CPUs from any generation.
Testing generic 32-bit kernels on 64-bit hardware remains possible,
just not building a 32-bit kernel that requires a 64-bit CPU.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20250226213714.4040853-5-arnd@kernel.org
This commit is contained in:
Arnd Bergmann 2025-02-26 22:37:08 +01:00 committed by Ingo Molnar
parent fc2d5cbe54
commit f388f60ca9
5 changed files with 18 additions and 104 deletions

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@ -1,9 +1,9 @@
# SPDX-License-Identifier: GPL-2.0
# Put here option for CPU selection and depending optimization
choice
prompt "Processor family"
default M686 if X86_32
default GENERIC_CPU if X86_64
prompt "x86-32 Processor family"
depends on X86_32
default M686
help
This is the processor type of your CPU. This information is
used for optimizing purposes. In order to compile a kernel
@ -31,7 +31,6 @@ choice
- "Pentium-4" for the Intel Pentium 4 or P4-based Celeron.
- "K6" for the AMD K6, K6-II and K6-III (aka K6-3D).
- "Athlon" for the AMD K7 family (Athlon/Duron/Thunderbird).
- "Opteron/Athlon64/Hammer/K8" for all K8 and newer AMD CPUs.
- "Crusoe" for the Transmeta Crusoe series.
- "Efficeon" for the Transmeta Efficeon series.
- "Winchip-C6" for original IDT Winchip.
@ -42,13 +41,10 @@ choice
- "CyrixIII/VIA C3" for VIA Cyrix III or VIA C3.
- "VIA C3-2" for VIA C3-2 "Nehemiah" (model 9 and above).
- "VIA C7" for VIA C7.
- "Intel P4" for the Pentium 4/Netburst microarchitecture.
- "Core 2/newer Xeon" for all core2 and newer Intel CPUs.
- "Intel Atom" for the Atom-microarchitecture CPUs.
- "Generic-x86-64" for a kernel which runs on any x86-64 CPU.
See each option's help text for additional details. If you don't know
what to do, choose "486".
what to do, choose "Pentium-Pro".
config M486SX
bool "486SX"
@ -114,11 +110,11 @@ config MPENTIUMIII
extensions.
config MPENTIUMM
bool "Pentium M"
bool "Pentium M/Pentium Dual Core/Core Solo/Core Duo"
depends on X86_32
help
Select this for Intel Pentium M (not Pentium-4 M)
notebook chips.
"Merom" Core Solo/Duo notebook chips
config MPENTIUM4
bool "Pentium-4/Celeron(P4-based)/Pentium-4 M/older Xeon"
@ -139,22 +135,10 @@ config MPENTIUM4
-Mobile Pentium 4
-Mobile Pentium 4 M
-Extreme Edition (Gallatin)
-Prescott
-Prescott 2M
-Cedar Mill
-Presler
-Smithfiled
Xeons (Intel Xeon, Xeon MP, Xeon LV, Xeon MV) corename:
-Foster
-Prestonia
-Gallatin
-Nocona
-Irwindale
-Cranford
-Potomac
-Paxville
-Dempsey
config MK6
bool "K6/K6-II/K6-III"
@ -172,13 +156,6 @@ config MK7
some extended instructions, and passes appropriate optimization
flags to GCC.
config MK8
bool "Opteron/Athlon64/Hammer/K8"
help
Select this for an AMD Opteron or Athlon64 Hammer-family processor.
Enables use of some extended instructions, and passes appropriate
optimization flags to GCC.
config MCRUSOE
bool "Crusoe"
depends on X86_32
@ -258,42 +235,14 @@ config MVIAC7
Select this for a VIA C7. Selecting this uses the correct cache
shift and tells gcc to treat the CPU as a 686.
config MPSC
bool "Intel P4 / older Netburst based Xeon"
depends on X86_64
help
Optimize for Intel Pentium 4, Pentium D and older Nocona/Dempsey
Xeon CPUs with Intel 64bit which is compatible with x86-64.
Note that the latest Xeons (Xeon 51xx and 53xx) are not based on the
Netburst core and shouldn't use this option. You can distinguish them
using the cpu family field
in /proc/cpuinfo. Family 15 is an older Xeon, Family 6 a newer one.
config MCORE2
bool "Core 2/newer Xeon"
help
Select this for Intel Core 2 and newer Core 2 Xeons (Xeon 51xx and
53xx) CPUs. You can distinguish newer from older Xeons by the CPU
family in /proc/cpuinfo. Newer ones have 6 and older ones 15
(not a typo)
config MATOM
bool "Intel Atom"
help
Select this for the Intel Atom platform. Intel Atom CPUs have an
in-order pipelining architecture and thus can benefit from
accordingly optimized code. Use a recent GCC with specific Atom
support in order to fully benefit from selecting this option.
config GENERIC_CPU
bool "Generic-x86-64"
depends on X86_64
help
Generic x86-64 CPU.
Run equally well on all x86-64 CPUs.
endchoice
config X86_GENERIC
@ -317,8 +266,8 @@ config X86_INTERNODE_CACHE_SHIFT
config X86_L1_CACHE_SHIFT
int
default "7" if MPENTIUM4 || MPSC
default "6" if MK7 || MK8 || MPENTIUMM || MCORE2 || MATOM || MVIAC7 || X86_GENERIC || GENERIC_CPU
default "7" if MPENTIUM4
default "6" if MK7 || MPENTIUMM || MATOM || MVIAC7 || X86_GENERIC || X86_64
default "4" if MELAN || M486SX || M486 || MGEODEGX1
default "5" if MWINCHIP3D || MWINCHIPC6 || MCRUSOE || MEFFICEON || MCYRIXIII || MK6 || MPENTIUMIII || MPENTIUMII || M686 || M586MMX || M586TSC || M586 || MVIAC3_2 || MGEODE_LX
@ -336,35 +285,19 @@ config X86_ALIGNMENT_16
config X86_INTEL_USERCOPY
def_bool y
depends on MPENTIUM4 || MPENTIUMM || MPENTIUMIII || MPENTIUMII || M586MMX || X86_GENERIC || MK8 || MK7 || MEFFICEON || MCORE2
depends on MPENTIUM4 || MPENTIUMM || MPENTIUMIII || MPENTIUMII || M586MMX || X86_GENERIC || MK7 || MEFFICEON
config X86_USE_PPRO_CHECKSUM
def_bool y
depends on MWINCHIP3D || MWINCHIPC6 || MCYRIXIII || MK7 || MK6 || MPENTIUM4 || MPENTIUMM || MPENTIUMIII || MPENTIUMII || M686 || MK8 || MVIAC3_2 || MVIAC7 || MEFFICEON || MGEODE_LX || MCORE2 || MATOM
#
# P6_NOPs are a relatively minor optimization that require a family >=
# 6 processor, except that it is broken on certain VIA chips.
# Furthermore, AMD chips prefer a totally different sequence of NOPs
# (which work on all CPUs). In addition, it looks like Virtual PC
# does not understand them.
#
# As a result, disallow these if we're not compiling for X86_64 (these
# NOPs do work on all x86-64 capable chips); the list of processors in
# the right-hand clause are the cores that benefit from this optimization.
#
config X86_P6_NOP
def_bool y
depends on X86_64
depends on (MCORE2 || MPENTIUM4 || MPSC)
depends on MWINCHIP3D || MWINCHIPC6 || MCYRIXIII || MK7 || MK6 || MPENTIUM4 || MPENTIUMM || MPENTIUMIII || MPENTIUMII || M686 || MVIAC3_2 || MVIAC7 || MEFFICEON || MGEODE_LX || MATOM
config X86_TSC
def_bool y
depends on (MWINCHIP3D || MCRUSOE || MEFFICEON || MCYRIXIII || MK7 || MK6 || MPENTIUM4 || MPENTIUMM || MPENTIUMIII || MPENTIUMII || M686 || M586MMX || M586TSC || MK8 || MVIAC3_2 || MVIAC7 || MGEODEGX1 || MGEODE_LX || MCORE2 || MATOM) || X86_64
depends on (MWINCHIP3D || MCRUSOE || MEFFICEON || MCYRIXIII || MK7 || MK6 || MPENTIUM4 || MPENTIUMM || MPENTIUMIII || MPENTIUMII || M686 || M586MMX || M586TSC || MVIAC3_2 || MVIAC7 || MGEODEGX1 || MGEODE_LX || MATOM) || X86_64
config X86_HAVE_PAE
def_bool y
depends on MCRUSOE || MEFFICEON || MCYRIXIII || MPENTIUM4 || MPENTIUMM || MPENTIUMIII || MPENTIUMII || M686 || MK8 || MVIAC7 || MCORE2 || MATOM || X86_64
depends on MCRUSOE || MEFFICEON || MCYRIXIII || MPENTIUM4 || MPENTIUMM || MPENTIUMIII || MPENTIUMII || M686 || MVIAC7 || MATOM || X86_64
config X86_CMPXCHG64
def_bool y
@ -374,12 +307,12 @@ config X86_CMPXCHG64
# generates cmov.
config X86_CMOV
def_bool y
depends on (MK8 || MK7 || MCORE2 || MPENTIUM4 || MPENTIUMM || MPENTIUMIII || MPENTIUMII || M686 || MVIAC3_2 || MVIAC7 || MCRUSOE || MEFFICEON || X86_64 || MATOM || MGEODE_LX)
depends on (MK7 || MPENTIUM4 || MPENTIUMM || MPENTIUMIII || MPENTIUMII || M686 || MVIAC3_2 || MVIAC7 || MCRUSOE || MEFFICEON || MATOM || MGEODE_LX || X86_64)
config X86_MINIMUM_CPU_FAMILY
int
default "64" if X86_64
default "6" if X86_32 && (MPENTIUM4 || MPENTIUMM || MPENTIUMIII || MPENTIUMII || M686 || MVIAC3_2 || MVIAC7 || MEFFICEON || MATOM || MCORE2 || MK7 || MK8)
default "6" if X86_32 && (MPENTIUM4 || MPENTIUMM || MPENTIUMIII || MPENTIUMII || M686 || MVIAC3_2 || MVIAC7 || MEFFICEON || MATOM || MK7)
default "5" if X86_32 && X86_CMPXCHG64
default "4"

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@ -178,20 +178,8 @@ else
# Use -mskip-rax-setup if supported.
KBUILD_CFLAGS += $(call cc-option,-mskip-rax-setup)
# FIXME - should be integrated in Makefile.cpu (Makefile_32.cpu)
cflags-$(CONFIG_MK8) += -march=k8
cflags-$(CONFIG_MPSC) += -march=nocona
cflags-$(CONFIG_MCORE2) += -march=core2
cflags-$(CONFIG_MATOM) += -march=atom
cflags-$(CONFIG_GENERIC_CPU) += -march=x86-64 -mtune=generic
KBUILD_CFLAGS += $(cflags-y)
rustflags-$(CONFIG_MK8) += -Ctarget-cpu=k8
rustflags-$(CONFIG_MPSC) += -Ctarget-cpu=nocona
rustflags-$(CONFIG_MCORE2) += -Ctarget-cpu=core2
rustflags-$(CONFIG_MATOM) += -Ctarget-cpu=atom
rustflags-$(CONFIG_GENERIC_CPU) += -Ctarget-cpu=x86-64 -Ztune-cpu=generic
KBUILD_RUSTFLAGS += $(rustflags-y)
KBUILD_CFLAGS += -march=x86-64 -mtune=generic
KBUILD_RUSTFLAGS += -Ctarget-cpu=x86-64 -Ztune-cpu=generic
KBUILD_CFLAGS += -mno-red-zone
KBUILD_CFLAGS += -mcmodel=kernel

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@ -24,7 +24,6 @@ cflags-$(CONFIG_MK6) += -march=k6
# Please note, that patches that add -march=athlon-xp and friends are pointless.
# They make zero difference whatsosever to performance at this time.
cflags-$(CONFIG_MK7) += -march=athlon
cflags-$(CONFIG_MK8) += $(call cc-option,-march=k8,-march=athlon)
cflags-$(CONFIG_MCRUSOE) += -march=i686 $(align)
cflags-$(CONFIG_MEFFICEON) += -march=i686 $(call tune,pentium3) $(align)
cflags-$(CONFIG_MWINCHIPC6) += $(call cc-option,-march=winchip-c6,-march=i586)
@ -32,9 +31,7 @@ cflags-$(CONFIG_MWINCHIP3D) += $(call cc-option,-march=winchip2,-march=i586)
cflags-$(CONFIG_MCYRIXIII) += $(call cc-option,-march=c3,-march=i486) $(align)
cflags-$(CONFIG_MVIAC3_2) += $(call cc-option,-march=c3-2,-march=i686)
cflags-$(CONFIG_MVIAC7) += -march=i686
cflags-$(CONFIG_MCORE2) += -march=i686 $(call tune,core2)
cflags-$(CONFIG_MATOM) += $(call cc-option,-march=atom,$(call cc-option,-march=core2,-march=i686)) \
$(call cc-option,-mtune=atom,$(call cc-option,-mtune=generic))
cflags-$(CONFIG_MATOM) += -march=atom
# AMD Elan support
cflags-$(CONFIG_MELAN) += -march=i486

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@ -15,8 +15,6 @@
#define MODULE_PROC_FAMILY "586TSC "
#elif defined CONFIG_M586MMX
#define MODULE_PROC_FAMILY "586MMX "
#elif defined CONFIG_MCORE2
#define MODULE_PROC_FAMILY "CORE2 "
#elif defined CONFIG_MATOM
#define MODULE_PROC_FAMILY "ATOM "
#elif defined CONFIG_M686
@ -33,8 +31,6 @@
#define MODULE_PROC_FAMILY "K6 "
#elif defined CONFIG_MK7
#define MODULE_PROC_FAMILY "K7 "
#elif defined CONFIG_MK8
#define MODULE_PROC_FAMILY "K8 "
#elif defined CONFIG_MELAN
#define MODULE_PROC_FAMILY "ELAN "
#elif defined CONFIG_MCRUSOE

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@ -3,7 +3,7 @@
config INTEL_MEI
tristate "Intel Management Engine Interface"
depends on X86 && PCI
default GENERIC_CPU || MCORE2 || MATOM || X86_GENERIC
default X86_64 || MATOM
help
The Intel Management Engine (Intel ME) provides Manageability,
Security and Media services for system containing Intel chipsets.