[PATCH v2 04/11] x86: drop configuration options for early 64-bit CPUs

From: Arnd Bergmann
Date: Tue Dec 10 2024 - 09:50:57 EST

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From: Arnd Bergmann <arnd@xxxxxxxx>

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@xxxxxxxx>
---
arch/x86/Kconfig.cpu | 95 +++++----------------------------
arch/x86/Makefile | 16 +-----
arch/x86/Makefile_32.cpu | 5 +-
arch/x86/include/asm/vermagic.h | 4 --
drivers/misc/mei/Kconfig | 2 +-
5 files changed, 18 insertions(+), 104 deletions(-)

diff --git a/arch/x86/Kconfig.cpu b/arch/x86/Kconfig.cpu
index 42e6a40876ea..8fcb8ccee44b 100644
--- a/arch/x86/Kconfig.cpu
+++ b/arch/x86/Kconfig.cpu
@@ -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"

diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index 5af3172fd51c..8120085b00a4 100644
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -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
diff --git a/arch/x86/Makefile_32.cpu b/arch/x86/Makefile_32.cpu
index 94834c4b5e5e..af7de9a42752 100644
--- a/arch/x86/Makefile_32.cpu
+++ b/arch/x86/Makefile_32.cpu
@@ -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
diff --git a/arch/x86/include/asm/vermagic.h b/arch/x86/include/asm/vermagic.h
index 75884d2cdec3..5d471253c755 100644
--- a/arch/x86/include/asm/vermagic.h
+++ b/arch/x86/include/asm/vermagic.h
@@ -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
diff --git a/drivers/misc/mei/Kconfig b/drivers/misc/mei/Kconfig
index 67d9391f1855..7575fee96cc6 100644
--- a/drivers/misc/mei/Kconfig
+++ b/drivers/misc/mei/Kconfig
@@ -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.
--
2.39.5

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