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| author | Andrew Cooper <andrew.cooper3@citrix.com> | 2025-11-26 15:51:47 +0300 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2025-12-14 11:57:13 +0300 |
| commit | 0bc03750deefc5fdab77b01c459bb1691c64c3c5 (patch) | |
| tree | 2443b567c90a8b5c80fae278ca82f3bf19c4526b | |
| parent | a2aabcfc6015b6196f161b6bf4df1519ab09c3e1 (diff) | |
| download | linux-0bc03750deefc5fdab77b01c459bb1691c64c3c5.tar.xz | |
x86/cpu: Drop vestigial PBE logic in AMD/Hygon/Centaur/Cyrix
Besides formatting changes, this logic dates back to Linux 2.4.0-test11 in
November 2000.
Prior to "Massive cleanup of CPU detection and bug handling",
c->x86_capability was a single u32 containing cpuid(1).edx,
cpuid(0x80000001).edx, or a synthesis thereof. X86_FEATURE_AMD3D was
defined as the top bit this single u32.
After "Massive cleanup of CPU detection and bug handling",
c->x86_capability became an array with AMD's extended feature leaf split
away from Intel's basic feature leaf.
AMD doc #20734-G states that 3DNow is only enumerated in the extended
feature leaf, and that other vendors where using this bit too. i.e. AMD
never produced a CPU which set bit 31 in the basic leaf, meaning that
there's nothing to clear out in the first place.
This logic looks like it was relevant in the pre-"Massive cleanup" world
but ought to have been dropped when c->x86_capability was properly split.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Pu Wen <puwen@hygon.cn>
Link: https://patch.msgid.link/20251126125147.880275-1-andrew.cooper3@citrix.com
| -rw-r--r-- | arch/x86/kernel/cpu/amd.c | 6 | ||||
| -rw-r--r-- | arch/x86/kernel/cpu/centaur.c | 6 | ||||
| -rw-r--r-- | arch/x86/kernel/cpu/cyrix.c | 6 | ||||
| -rw-r--r-- | arch/x86/kernel/cpu/hygon.c | 6 |
4 files changed, 0 insertions, 24 deletions
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c index c04f53f43af1..c792c2afd849 100644 --- a/arch/x86/kernel/cpu/amd.c +++ b/arch/x86/kernel/cpu/amd.c @@ -1051,12 +1051,6 @@ static void init_amd(struct cpuinfo_x86 *c) early_init_amd(c); - /* - * Bit 31 in normal CPUID used for nonstandard 3DNow ID; - * 3DNow is IDd by bit 31 in extended CPUID (1*32+31) anyway - */ - clear_cpu_cap(c, 0*32+31); - if (c->x86 >= 0x10) set_cpu_cap(c, X86_FEATURE_REP_GOOD); diff --git a/arch/x86/kernel/cpu/centaur.c b/arch/x86/kernel/cpu/centaur.c index a3b55db35c96..c8398940b975 100644 --- a/arch/x86/kernel/cpu/centaur.c +++ b/arch/x86/kernel/cpu/centaur.c @@ -119,12 +119,6 @@ static void init_centaur(struct cpuinfo_x86 *c) u32 fcr_clr = 0; u32 lo, hi, newlo; u32 aa, bb, cc, dd; - - /* - * Bit 31 in normal CPUID used for nonstandard 3DNow ID; - * 3DNow is IDd by bit 31 in extended CPUID (1*32+31) anyway - */ - clear_cpu_cap(c, 0*32+31); #endif early_init_centaur(c); init_intel_cacheinfo(c); diff --git a/arch/x86/kernel/cpu/cyrix.c b/arch/x86/kernel/cpu/cyrix.c index dfec2c61e354..8f22085c4dd2 100644 --- a/arch/x86/kernel/cpu/cyrix.c +++ b/arch/x86/kernel/cpu/cyrix.c @@ -195,12 +195,6 @@ static void init_cyrix(struct cpuinfo_x86 *c) char *buf = c->x86_model_id; const char *p = NULL; - /* - * Bit 31 in normal CPUID used for nonstandard 3DNow ID; - * 3DNow is IDd by bit 31 in extended CPUID (1*32+31) anyway - */ - clear_cpu_cap(c, 0*32+31); - /* Cyrix used bit 24 in extended (AMD) CPUID for Cyrix MMX extensions */ if (test_cpu_cap(c, 1*32+24)) { clear_cpu_cap(c, 1*32+24); diff --git a/arch/x86/kernel/cpu/hygon.c b/arch/x86/kernel/cpu/hygon.c index 1fda6c3a2b65..7f95a74e4c65 100644 --- a/arch/x86/kernel/cpu/hygon.c +++ b/arch/x86/kernel/cpu/hygon.c @@ -174,12 +174,6 @@ static void init_hygon(struct cpuinfo_x86 *c) early_init_hygon(c); - /* - * Bit 31 in normal CPUID used for nonstandard 3DNow ID; - * 3DNow is IDd by bit 31 in extended CPUID (1*32+31) anyway - */ - clear_cpu_cap(c, 0*32+31); - set_cpu_cap(c, X86_FEATURE_REP_GOOD); /* |