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Subject[PATCH] [RFC] [2.5 i386] GCC 3.1 -march support, PPRO_FENCE reduction, prefetch fixes and other CPU-related changes
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Date
This is a revised version of a patch I posted a few months ago and
implements all the suggestions that were posted in reply and several
other things.


This patch does the following:
- Modifies CPU choices texts to include processor features (e.g.
"586+MMX+TSC...Pentium-MMX")
- Splits Pentium2 and PentiumPro
- Splits K6 and K6-2/K6-3
- Splits Athlon and Athlon-SSE
- Splits 586 and 6x86MX
- Makes CONFIG_X86_PPRO_FENCE user-settable and disable if not SMP or
CPU incompatible with Pentium Pro selected
- Supports F0 0F bug workaround for all kernels that don't require 686
or 3DNow!
- Defines CONFIG_X86_{686,MMX{EXT,},SSE{2,},3DNOW{EXT,}}: all except
MMXEXT are currently unused (this is the reason for splitting
Athlon-SSE, 6x86MX and Pentium2)
- Updates and adds entries in Config.help
- Compiles K6s with -march=i586 -mcpu=i686 if -march=k6{-2,} is not
available (matches insn costs more closely)
- Replaces GCC tests in Makefile with calls to new cc_test function to
reduce redundancy
- Uses -march={pentium{-mmx,2,3,4},k6{-2,},athlon{-xp,}} when
appropriate and supported and adds -mno-{mmx,sse{2,}} to prevent
careless use of builtin and automatic use by compiler
- Adds panics for CONFIG_X86_{PPRO_FENCE,USE_SSE_PREFETCH,686,USE_3DNOW}
in bugs.h
- Enables prefetchnta when CONFIG_X86_USE_SSE_PREFETCH is defined, which
happens for Pentium3, Pentium4 and Athlon
- Causes Athlon to use prefetchnta rather than prefetch
- Adds Makefile entry for Elan (as 486)

I need help on these issues:
- I have read the specification update and Intel explicitly says that UP
systems are not affected, but the use of CONFIG_PPRO_FENCE in io.h might
indicate the contrary. Does anyone know if this is the case or not?
(patch assumes Intel is right)

- Is prefetchnta really better than prefetch on Athlons? (consider both
prefetch() and memcpy()) (patch assumes it is for prefetch() but doesn't
modify memcpy())

- The optimized memcpy routines seem seriously deficient: IMHO they
should be available in MMX, MMX+prefetch, MMX+prefetch+nt, SSE and SSE2
flavors rather than only MMX+prefetch and a partial version of
MMX+prefetch+nt (uses movntq but not prefetchnta). Any comments? Is
anyone doing this/did anyone already do this?

- Should I port this to 2.4?


diffstat:
arch/i386/config.in | 106 +++++++++++++++++++++++++++++++++---------
arch/i386/Config.help | 93 +++++++++++++++++++++++++++---------
arch/i386/Makefile | 43 ++++++++++++++---
include/asm-i386/bugs.h | 23 +++++++++
include/asm-i386/processor.h | 9 ++-
arch/i386/kernel/cpu/common.c | 4 +
arch/i386/lib/mmx.c | 2
7 files changed, 224 insertions(+), 56 deletions(-)

diff --exclude-from=/home/ldb/src/linux-exclude -urNd a/arch/i386/Config.help b/arch/i386/Config.help
--- a/arch/i386/Config.help 2002-07-20 21:11:07.000000000 +0200
+++ b/arch/i386/Config.help 2002-08-04 07:37:29.000000000 +0200
@@ -403,14 +403,18 @@
- "486" for the AMD/Cyrix/IBM/Intel 486DX/DX2/DX4 or
SL/SLC/SLC2/SLC3/SX/SX2 and UMC U5D or U5S.
- "586" for generic Pentium CPUs lacking the TSC
- (time stamp counter) register.
- - "Pentium-Classic" for the Intel Pentium.
- - "Pentium-MMX" for the Intel Pentium MMX.
- - "Pentium-Pro" for the Intel Pentium Pro/Celeron/Pentium II.
+ (time stamp counter) register and MMX instructions.
+ - 6x86MX for the 6x86MX and generic Pentium CPUs lacking the TSC
+ but with MMX instructions.
+ - "Pentium-Classic" for the Intel Pentium (586 with TSC).
+ - "Pentium-MMX" for the Intel Pentium MMX (586 with TSC+MMX).
+ - "Pentium-Pro" for the Intel Pentium Pro/Celeron.
+ - "Pentium-II" for the Intel Pentium II.
- "Pentium-III" for the Intel Pentium III
and Celerons based on the Coppermine core.
- "Pentium-4" for the Intel Pentium 4.
- - "K6" for the AMD K6, K6-II and K6-III (aka K6-3D).
+ - "K6" for the AMD K6
+ - "K6-2" for the K6-II and K6-III (aka K6-3D).
- "Athlon" for the AMD K7 family (Athlon/Duron/Thunderbird).
- "Crusoe" for the Transmeta Crusoe series.
- "Winchip-C6" for original IDT Winchip.
@@ -418,7 +422,9 @@
- "Winchip-2A" for IDT Winchips with 3dNow! capabilities.
- "CyrixIII" for VIA Cyrix III or VIA C3.

- If you don't know what to do, choose "386".
+ If you don't know what to do, type "cat /proc/cpuinfo" or open the
+ case and look at the processor. If you are building a generic
+ kernel or don't have access to the target machine, choose "386".

CONFIG_M486
Select this for a x486 processor, ether Intel or one of the
@@ -431,18 +437,38 @@
Intel 5x86 or 6x86, or the Intel 6x86MX. This choice does not
assume the RDTSC (Read Time Stamp Counter) instruction.

+CONFIG_M586MX
+ Select this for the NexGen 6x86MX and other Pentium-class processors
+ with the MMX graphics/multimedia extended instructions but without
+ the RDTSC (Read Time Stamp Counter) instruction.
+
CONFIG_M586TSC
Select this for a Pentium Classic processor with the RDTSC (Read
Time Stamp Counter) instruction for benchmarking.

CONFIG_M586MMX
Select this for a Pentium with the MMX graphics/multimedia
- extended instructions.
+ extended instructions and with the RDTSC (Read Time Stamp Counter)
+ instruction for benchmarking.

CONFIG_M686
- Select this for a Pro/Celeron/Pentium II. This enables the use of
- Pentium Pro extended instructions, and disables the init-time guard
- against the f00f bug found in earlier Pentiums.
+ Select this for a non-Intel/AMD 686 processor without MMX support
+ support. This enables the use of Pentium Pro extended instructions
+ and disables the init-time guard against the f00f bug found in
+ earlier Pentiums.
+
+CONFIG_MPENTIUMPRO
+ Select this for a Pentium Pro or Celeron. This enables the use of
+ Pentium Pro extended instructions, disables the init-time guard
+ against the f00f bug found in earlier Pentiums and enables the
+ workaround for the Pentium Pro store ordering bug.
+
+CONFIG_MPENTIUMII
+ Select this for a Pentium II or another 686 processor with MMX
+ support. This enables the use of Pentium Pro extended instructions,
+ disables the init-time guard against the f00f bug found in earlier
+ Pentiums and disables the workaround for the Pentium Pro store
+ ordering bug.

CONFIG_MPENTIUMIII
Select this for Intel chips based on the Pentium-III and
@@ -450,9 +476,10 @@
instructions, in addition to the Pentium II extensions.

CONFIG_MPENTIUM4
- Select this for Intel Pentium 4 chips. Presently these are
- treated almost like Pentium IIIs, but with a different cache
- shift.
+ Select this for Intel Pentium 4 chips. They have a different cache
+ shift and if you are compiling with GCC 3.1 or later instructions
+ will be selected and ordered specifically for maximum performance on
+ the Intel Pentium 4.

CONFIG_MCRUSOE
Select this for Transmeta Crusoe processor. Treats the processor
@@ -460,14 +487,18 @@
Pentium Pro with no alignment requirements).

CONFIG_MK6
- Select this for an AMD K6-family processor. Enables use of
- some extended instructions, and passes appropriate optimization
- flags to GCC.
+ Select this for an AMD K6 processor. Enables use of some extended
+ instructions, and passes appropriate optimization flags to GCC.
+
+CONFIG_MK6
+ Select this for an AMD K6-2/K6-3D or K6-3. Enables use of some
+ extended instructions, passes appropriate optimization flags to GCC
+ and enables 3DNow!

CONFIG_MK7
Select this for an AMD Athlon K7-family processor. Enables use of
- some extended instructions, and passes appropriate optimization
- flags to GCC.
+ some extended instructions, passes appropriate optimization flags to
+ GCC and enables 3DNow!

CONFIG_MCYRIXIII
Select this for a Cyrix III or C3 chip. Presently Linux and GCC
@@ -477,20 +508,34 @@

CONFIG_MWINCHIPC6
Select this for a IDT Winchip C6 chip. Linux and GCC
- treat this chip as a 586TSC with some extended instructions
- and alignment requirements.
+ treat this chip as a 586 with some extended instructions
+ and alignment requirements. Development kernels also enable
+ out of order memory stores for this CPU, which can increase
+ performance of some operations.

CONFIG_MWINCHIP2
Select this for a IDT Winchip-2. Linux and GCC
treat this chip as a 586TSC with some extended instructions
- and alignment requirements.
+ and alignment requirements. Development kernels also enable
+ out of order memory stores for this CPU, which can increase
+ performance of some operations.

CONFIG_MWINCHIP3D
Select this for a IDT Winchip-2A or 3. Linux and GCC
treat this chip as a 586TSC with some extended instructions
- and alignment reqirements. Development kernels also enable
- out of order memory stores for this CPU, which can increase
- performance of some operations.
+ and alignment reqirements and with 3DNow! support. Development
+ kernels also enable out of order memory stores for this CPU, which
+ can increase performance of some operations.
+
+CONFIG_X86_PPRO_FENCE
+ Allows the kernel to run on Pentium Pro SMP systems by supporting a
+ workaround for the store ordering bug present on them.
+ This slows down all processors except WinChips since they already do
+ out-of-order stores.
+
+ If you don't know what to do, type "cat /proc/cpuinfo" or open the
+ case and look at the processor. If you are building a generic
+ kernel or don't have access to the target machine, choose Y.

CONFIG_VGA_CONSOLE
Saying Y here will allow you to use Linux in text mode through a
diff --exclude-from=/home/ldb/src/linux-exclude -urNd a/arch/i386/config.in b/arch/i386/config.in
--- a/arch/i386/config.in 2002-07-29 04:22:22.000000000 +0200
+++ b/arch/i386/config.in 2002-08-04 14:59:39.000000000 +0200
@@ -17,20 +17,24 @@
choice 'Processor family' \
"386 CONFIG_M386 \
486 CONFIG_M486 \
- 586/K5/5x86/6x86/6x86MX CONFIG_M586 \
- Pentium-Classic CONFIG_M586TSC \
- Pentium-MMX CONFIG_M586MMX \
- Pentium-Pro/Celeron/Pentium-II CONFIG_M686 \
- Pentium-III/Celeron(Coppermine) CONFIG_MPENTIUMIII \
+ 586/K5/5x86/6x86 CONFIG_M586 \
+ 586+MMX...6x86MX CONFIG_M586MX \
+ 586+TSC...Pentium-Classic CONFIG_M586TSC \
+ 586+TSC+MMX...Pentium-MMX CONFIG_M586MMX \
+ 686...Pentium-Pro/Celeron CONFIG_M686 \
+ 686+MMX...Pentium-II CONFIG_MPENTIUMII \
+ 686+SSE...Pentium-III/Celeron(Coppermine) CONFIG_MPENTIUMIII \
Pentium-4 CONFIG_MPENTIUM4 \
- K6/K6-II/K6-III CONFIG_MK6 \
- Athlon/Duron/K7 CONFIG_MK7 \
+ K6 CONFIG_MK6 \
+ K6-II/K6-III CONFIG_MK6II \
+ K7...Athlon/Duron CONFIG_MK7 \
+ K7+SSE...Athlon-4/XP/MP CONFIG_MK7SSE \
Elan CONFIG_MELAN \
Crusoe CONFIG_MCRUSOE \
Winchip-C6 CONFIG_MWINCHIPC6 \
- Winchip-2 CONFIG_MWINCHIP2 \
- Winchip-2A/Winchip-3 CONFIG_MWINCHIP3D \
- CyrixIII/C3 CONFIG_MCYRIXIII" Pentium-Pro
+ Winchip+TSC...Winchip-2 CONFIG_MWINCHIP2 \
+ Winchip+TSC+3DNow...Winchip-2A/Winchip-3 CONFIG_MWINCHIP3D \
+ CyrixIII/C3 CONFIG_MCYRIXIII" Pentium-III
#
# Define implied options from the CPU selection here
#
@@ -41,8 +45,6 @@
define_int CONFIG_X86_L1_CACHE_SHIFT 4
define_bool CONFIG_RWSEM_GENERIC_SPINLOCK y
define_bool CONFIG_RWSEM_XCHGADD_ALGORITHM n
- define_bool CONFIG_X86_PPRO_FENCE y
- define_bool CONFIG_X86_F00F_BUG y
else
define_bool CONFIG_X86_WP_WORKS_OK y
define_bool CONFIG_X86_INVLPG y
@@ -57,23 +59,23 @@
define_int CONFIG_X86_L1_CACHE_SHIFT 4
define_bool CONFIG_X86_USE_STRING_486 y
define_bool CONFIG_X86_ALIGNMENT_16 y
- define_bool CONFIG_X86_PPRO_FENCE y
- define_bool CONFIG_X86_F00F_BUG y
fi
if [ "$CONFIG_M586" = "y" ]; then
define_int CONFIG_X86_L1_CACHE_SHIFT 5
define_bool CONFIG_X86_USE_STRING_486 y
define_bool CONFIG_X86_ALIGNMENT_16 y
- define_bool CONFIG_X86_PPRO_FENCE y
- define_bool CONFIG_X86_F00F_BUG y
+fi
+if [ "$CONFIG_M586MX" = "y" ]; then
+ define_int CONFIG_X86_L1_CACHE_SHIFT 5
+ define_bool CONFIG_X86_USE_STRING_486 y
+ define_bool CONFIG_X86_ALIGNMENT_16 y
+ define_bool CONFIG_X86_MMX y
fi
if [ "$CONFIG_M586TSC" = "y" ]; then
define_int CONFIG_X86_L1_CACHE_SHIFT 5
define_bool CONFIG_X86_USE_STRING_486 y
define_bool CONFIG_X86_ALIGNMENT_16 y
define_bool CONFIG_X86_TSC y
- define_bool CONFIG_X86_PPRO_FENCE y
- define_bool CONFIG_X86_F00F_BUG y
fi
if [ "$CONFIG_M586MMX" = "y" ]; then
define_int CONFIG_X86_L1_CACHE_SHIFT 5
@@ -81,33 +83,60 @@
define_bool CONFIG_X86_ALIGNMENT_16 y
define_bool CONFIG_X86_TSC y
define_bool CONFIG_X86_GOOD_APIC y
- define_bool CONFIG_X86_PPRO_FENCE y
- define_bool CONFIG_X86_F00F_BUG y
+ define_bool CONFIG_X86_MMX y
fi
if [ "$CONFIG_M686" = "y" ]; then
define_int CONFIG_X86_L1_CACHE_SHIFT 5
define_bool CONFIG_X86_TSC y
define_bool CONFIG_X86_GOOD_APIC y
define_bool CONFIG_X86_USE_PPRO_CHECKSUM y
- define_bool CONFIG_X86_PPRO_FENCE y
+ define_bool CONFIG_X86_686 y
+fi
+if [ "$CONFIG_MPENTIUMII" = "y" ]; then
+ define_int CONFIG_X86_L1_CACHE_SHIFT 5
+ define_bool CONFIG_X86_TSC y
+ define_bool CONFIG_X86_GOOD_APIC y
+ define_bool CONFIG_X86_USE_PPRO_CHECKSUM y
+ define_bool CONFIG_X86_686 y
+ define_bool CONFIG_X86_MMX y
fi
if [ "$CONFIG_MPENTIUMIII" = "y" ]; then
define_int CONFIG_X86_L1_CACHE_SHIFT 5
define_bool CONFIG_X86_TSC y
define_bool CONFIG_X86_GOOD_APIC y
define_bool CONFIG_X86_USE_PPRO_CHECKSUM y
+ define_bool CONFIG_X86_686 y
+ define_bool CONFIG_X86_MMX y
+ define_bool CONFIG_X86_MMXEXT y
+ define_bool CONFIG_X86_SSE y
+ define_bool CONFIG_X86_USE_SSE_PREFETCH y
fi
if [ "$CONFIG_MPENTIUM4" = "y" ]; then
define_int CONFIG_X86_L1_CACHE_SHIFT 7
define_bool CONFIG_X86_TSC y
define_bool CONFIG_X86_GOOD_APIC y
define_bool CONFIG_X86_USE_PPRO_CHECKSUM y
+ define_bool CONFIG_X86_686 y
+ define_bool CONFIG_X86_MMX y
+ define_bool CONFIG_X86_MMXEXT y
+ define_bool CONFIG_X86_SSE y
+ define_bool CONFIG_X86_SSE2 y
+ define_bool CONFIG_X86_USE_SSE_PREFETCH y
fi
if [ "$CONFIG_MK6" = "y" ]; then
define_int CONFIG_X86_L1_CACHE_SHIFT 5
define_bool CONFIG_X86_ALIGNMENT_16 y
define_bool CONFIG_X86_TSC y
define_bool CONFIG_X86_USE_PPRO_CHECKSUM y
+ define_bool CONFIG_X86_MMX y
+fi
+if [ "$CONFIG_MK6II" = "y" ]; then
+ define_int CONFIG_X86_L1_CACHE_SHIFT 5
+ define_bool CONFIG_X86_ALIGNMENT_16 y
+ define_bool CONFIG_X86_TSC y
+ define_bool CONFIG_X86_USE_PPRO_CHECKSUM y
+ define_bool CONFIG_X86_MMX y
+ define_bool CONFIG_X86_3DNOW y
fi
if [ "$CONFIG_MK7" = "y" ]; then
define_int CONFIG_X86_L1_CACHE_SHIFT 6
@@ -115,6 +144,26 @@
define_bool CONFIG_X86_GOOD_APIC y
define_bool CONFIG_X86_USE_3DNOW y
define_bool CONFIG_X86_USE_PPRO_CHECKSUM y
+ define_bool CONFIG_X86_686 y
+ define_bool CONFIG_X86_MMX y
+ define_bool CONFIG_X86_MMXEXT y
+ define_bool CONFIG_X86_3DNOW y
+ define_bool CONFIG_X86_3DNOWEXT y
+ define_bool CONFIG_X86_USE_SSE_PREFETCH y
+fi
+if [ "$CONFIG_MK7SSE" = "y" ]; then
+ define_int CONFIG_X86_L1_CACHE_SHIFT 6
+ define_bool CONFIG_X86_TSC y
+ define_bool CONFIG_X86_GOOD_APIC y
+ define_bool CONFIG_X86_USE_3DNOW y
+ define_bool CONFIG_X86_USE_PPRO_CHECKSUM y
+ define_bool CONFIG_X86_686 y
+ define_bool CONFIG_X86_MMX y
+ define_bool CONFIG_X86_MMXEXT y
+ define_bool CONFIG_X86_3DNOW y
+ define_bool CONFIG_X86_3DNOWEXT y
+ define_bool CONFIG_X86_SSE y
+ define_bool CONFIG_X86_USE_SSE_PREFETCH y
fi
if [ "$CONFIG_MELAN" = "y" ]; then
define_int CONFIG_X86_L1_CACHE_SHIFT 4
@@ -127,16 +176,20 @@
define_bool CONFIG_X86_ALIGNMENT_16 y
define_bool CONFIG_X86_USE_3DNOW y
define_bool CONFIG_X86_USE_PPRO_CHECKSUM y
+ define_bool CONFIG_X86_MMX y
+ define_bool CONFIG_X86_3DNOW y
fi
if [ "$CONFIG_MCRUSOE" = "y" ]; then
define_int CONFIG_X86_L1_CACHE_SHIFT 5
define_bool CONFIG_X86_TSC y
+ define_bool CONFIG_X86_686 y
fi
if [ "$CONFIG_MWINCHIPC6" = "y" ]; then
define_int CONFIG_X86_L1_CACHE_SHIFT 5
define_bool CONFIG_X86_ALIGNMENT_16 y
define_bool CONFIG_X86_USE_PPRO_CHECKSUM y
define_bool CONFIG_X86_OOSTORE y
+ define_bool CONFIG_X86_MMX y
fi
if [ "$CONFIG_MWINCHIP2" = "y" ]; then
define_int CONFIG_X86_L1_CACHE_SHIFT 5
@@ -144,6 +197,7 @@
define_bool CONFIG_X86_TSC y
define_bool CONFIG_X86_USE_PPRO_CHECKSUM y
define_bool CONFIG_X86_OOSTORE y
+ define_bool CONFIG_X86_MMX y
fi
if [ "$CONFIG_MWINCHIP3D" = "y" ]; then
define_int CONFIG_X86_L1_CACHE_SHIFT 5
@@ -151,6 +205,16 @@
define_bool CONFIG_X86_TSC y
define_bool CONFIG_X86_USE_PPRO_CHECKSUM y
define_bool CONFIG_X86_OOSTORE y
+ define_bool CONFIG_X86_MMX y
+ define_bool CONFIG_X86_3DNOW y
+fi
+
+# Enable workarounds if kernel would not panic on an affected processor
+if [ "$CONFIG_X86_686" != "y" -a "$CONFIG_X86_USE_3DNOW" != "y" ]; then
+ define_bool CONFIG_X86_F00F_BUG y
+fi
+if [ "$CONFIG_X86_USE_SSE_PREFETCH" != "y" -a "$CONFIG_X86_USE_3DNOW" != "y" -a "$CONFIG_X86_OOSTORE" != "y" ]; then
+ dep_bool 'Support Pentium Pro SMP and slow down all processors' CONFIG_X86_PPRO_FENCE $CONFIG_SMP
fi

bool 'Symmetric multi-processing support' CONFIG_SMP
diff --exclude-from=/home/ldb/src/linux-exclude -urNd a/arch/i386/kernel/cpu/common.c b/arch/i386/kernel/cpu/common.c
--- a/arch/i386/kernel/cpu/common.c 2002-07-29 04:18:06.000000000 +0200
+++ b/arch/i386/kernel/cpu/common.c 2002-08-04 09:58:15.000000000 +0200
@@ -299,6 +299,10 @@
clear_bit(X86_FEATURE_TSC, c->x86_capability);
#endif

+ /* Intel SSE-capable processors have all AMD MMX extensions */
+ if(test_bit(X86_FEATURE_XMM, c->x86_capability))
+ set_bit(X86_FEATURE_MMXEXT, c->x86_capability);
+
/* FXSR disabled? */
if (disable_x86_fxsr) {
clear_bit(X86_FEATURE_FXSR, c->x86_capability);
diff --exclude-from=/home/ldb/src/linux-exclude -urNd a/arch/i386/lib/mmx.c b/arch/i386/lib/mmx.c
--- a/arch/i386/lib/mmx.c 2002-07-20 21:11:20.000000000 +0200
+++ b/arch/i386/lib/mmx.c 2002-08-04 09:58:49.000000000 +0200
@@ -121,7 +121,7 @@
return p;
}

-#ifdef CONFIG_MK7
+#ifdef CONFIG_X86_MMXEXT

/*
* The K7 has streaming cache bypass load/store. The Cyrix III, K6 and
diff --exclude-from=/home/ldb/src/linux-exclude -urNd a/arch/i386/Makefile b/arch/i386/Makefile
--- a/arch/i386/Makefile 2002-07-20 21:11:13.000000000 +0200
+++ b/arch/i386/Makefile 2002-08-04 15:51:08.000000000 +0200
@@ -20,10 +20,20 @@
OBJCOPYFLAGS := -O binary -R .note -R .comment -S
LDFLAGS_vmlinux := -T arch/i386/vmlinux.lds -e stext

+__cc_test = if $(CC) $(1) -S -o /dev/null -xc /dev/null >/dev/null 2>&1; then echo "$(1)"; $(2)fi
+cc_test = $(call __cc_test,$(1),)
+cc_test_ = $(call __cc_test,$(1),else $(2); )
+cc_test_march = $(call cc_test_,-march=$(1),echo "-march=$(2)")
+cc_test_march3 = $(call cc_test_,-march=$(1),$(call cc_test_march,$(2),$(3)))
+
CFLAGS += -pipe

# prevent gcc from keeping the stack 16 byte aligned
-CFLAGS += $(shell if $(CC) -mpreferred-stack-boundary=2 -S -o /dev/null -xc /dev/null >/dev/null 2>&1; then echo "-mpreferred-stack-boundary=2"; fi)
+CFLAGS += $(shell $(call cc_test,-mpreferred-stack-boundary=2))
+
+# MMX, SSE and SSE2 are disabled to prevent use by compiler (that could clobber user registers and cause unexpected oopses)
+# and because builtins must not be used until we require GCC 3.1
+CFLAGS += $(shell $(call cc_test,-mno-mmx -mno-sse -mno-sse2))

ifdef CONFIG_M386
CFLAGS += -march=i386
@@ -33,6 +43,10 @@
CFLAGS += -march=i486
endif

+ifdef CONFIG_MELAN
+CFLAGS += -march=i486
+endif
+
ifdef CONFIG_M586
CFLAGS += -march=i586
endif
@@ -41,32 +55,48 @@
CFLAGS += -march=i586
endif

+ifdef CONFIG_M586MX
+CFLAGS += $(shell $(call cc_test_march,pentium-mmx,i586))
+endif
+
ifdef CONFIG_M586MMX
-CFLAGS += -march=i586
+CFLAGS += $(shell $(call cc_test_march,pentium-mmx,i586))
endif

ifdef CONFIG_M686
CFLAGS += -march=i686
endif

+ifdef CONFIG_MPENTIUMII
+CFLAGS += $(shell $(call cc_test_march,pentium2,i686))
+endif
+
ifdef CONFIG_MPENTIUMIII
-CFLAGS += -march=i686
+CFLAGS += $(shell $(call cc_test_march,pentium3,i686))
endif

ifdef CONFIG_MPENTIUM4
-CFLAGS += -march=i686
+CFLAGS += $(shell $(call cc_test_march,pentium4,i686))
endif

ifdef CONFIG_MK6
-CFLAGS += $(shell if $(CC) -march=k6 -S -o /dev/null -xc /dev/null >/dev/null 2>&1; then echo "-march=k6"; else echo "-march=i586"; fi)
+CFLAGS += $(shell $(call cc_test_march,k6,i586 -mcpu=i686))
+endif
+
+ifdef CONFIG_MK6II
+CFLAGS += $(shell $(call cc_test_march3,k6-2,k6,i586 -mcpu=i686))
endif

ifdef CONFIG_MK7
-CFLAGS += $(shell if $(CC) -march=athlon -S -o /dev/null -xc /dev/null >/dev/null 2>&1; then echo "-march=athlon"; else echo "-march=i686 -malign-functions=4"; fi)
+CFLAGS += $(shell $(call cc_test_march,athlon,i686))
+endif
+
+ifdef CONFIG_MK7SSE
+CFLAGS += $(shell $(call cc_test_march3,athlon-xp,athlon,i686))
endif

ifdef CONFIG_MCRUSOE
-CFLAGS += -march=i686 -malign-functions=0 -malign-jumps=0 -malign-loops=0
+CFLAGS += $(shell $(call cc_test_march,crusoe,i686 -malign-functions=0 -malign-jumps=0 -malign-loops=0))
endif

ifdef CONFIG_MWINCHIPC6
diff --exclude-from=/home/ldb/src/linux-exclude -urNd a/include/asm-i386/bugs.h b/include/asm-i386/bugs.h
--- a/include/asm-i386/bugs.h 2002-07-20 21:11:09.000000000 +0200
+++ b/include/asm-i386/bugs.h 2002-08-04 15:27:40.000000000 +0200
@@ -171,6 +171,11 @@
panic("Kernel requires i486+ for 'invlpg' and other features");
#endif

+#if defined(CONFIG_X86_686)
+ if(boot_cpu_data.x86 < 6)
+ panic("Kernel requires 686+ for cmov");
+#endif
+
/*
* If we configured ourselves for a TSC, we'd better have one!
*/
@@ -193,6 +198,24 @@
&& (boot_cpu_data.x86_mask < 6 || boot_cpu_data.x86_mask == 11))
panic("Kernel compiled for PMMX+, assumes a local APIC without the read-before-write bug!");
#endif
+
+#if !defined(CONFIG_X86_PPRO_FENCE) && defined(CONFIG_SMP)
+ if(boot_cpu_data.x86_vendor == X86_VENDOR_INTEL
+ && boot_cpu_data.x86 == 6
+ && boot_cpu_data.x86_model <= 1
+ )
+ panic("Kernel compiled without Pentium Pro SMP support!");
+#endif
+
+#if defined(CONFIG_X86_USE_3DNOW)
+ if(!boot_cpu_has(X86_FEATURE_3DNOW))
+ panic("Kernel requires 3DNow support (K6-2/3, Athlon)");
+#endif
+
+#if defined(CONFIG_X86_USE_SSE_PREFETCH)
+ if(!boot_cpu_has(X86_FEATURE_MMXEXT))
+ panic("Kernel requires extended MMX support (Pentium3/4, Athlon)");
+#endif
}

static void __init check_bugs(void)
diff --exclude-from=/home/ldb/src/linux-exclude -urNd a/include/asm-i386/processor.h b/include/asm-i386/processor.h
--- a/include/asm-i386/processor.h 2002-08-02 01:19:14.000000000 +0200
+++ b/include/asm-i386/processor.h 2002-08-03 13:41:03.000000000 +0200
@@ -464,7 +464,7 @@
#define cpu_relax() rep_nop()

/* Prefetch instructions for Pentium III and AMD Athlon */
-#ifdef CONFIG_MPENTIUMIII
+#ifdef CONFIG_X86_USE_SSE_PREFETCH

#define ARCH_HAS_PREFETCH
extern inline void prefetch(const void *x)
@@ -475,13 +475,16 @@
#elif CONFIG_X86_USE_3DNOW

#define ARCH_HAS_PREFETCH
-#define ARCH_HAS_PREFETCHW
-#define ARCH_HAS_SPINLOCK_PREFETCH

extern inline void prefetch(const void *x)
{
__asm__ __volatile__ ("prefetch (%0)" : : "r"(x));
}
+#endif
+
+#ifdef CONFIG_X86_USE_3DNOW
+#define ARCH_HAS_PREFETCHW
+#define ARCH_HAS_SPINLOCK_PREFETCH

extern inline void prefetchw(const void *x)
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