Fine tune the code that decides when to use CPUID. For now, use it

only for Athlon model 1, 2, 3, or 4 processors.  According to AMD, the
model 6 is OK, and perhaps the model 7 as well.  The model 4 is known
to be bad, and models 1, 2, and 3 are probably bad too.  No Intel
processors are known to be bad.

diff --git a/v7/src/microcode/cmpauxmd/i386.m4 b/v7/src/microcode/cmpauxmd/i386.m4
index 767c054960728f1f3568493d616a27133c3277f4..10995a6e403cbda06d4a4e59254a3664b34e210c 100644 (file)
--- a/v7/src/microcode/cmpauxmd/i386.m4
+++ b/v7/src/microcode/cmpauxmd/i386.m4
@@ -1,6 +1,6 @@
 ### -*-Midas-*-
 ###
-### $Id: i386.m4,v 1.53 2001/12/17 19:41:58 cph Exp $
+### $Id: i386.m4,v 1.54 2001/12/17 20:27:54 cph Exp $
 ###
 ### Copyright (c) 1992-2001 Massachusetts Institute of Technology
 ###
@@ -446,11 +446,6 @@ i386_initialize_no_fp:
 
        OP(mov,l)       TW(IMM(HEX(00000001)),ABS(EVR(ia32_cpuid_supported)))
 
-# By default, use CPUID for synchronization.
-# We will disable this for known processors.
-
-       OP(mov,l)       TW(IMM(HEX(00000001)),ABS(EVR(ia32_cpuid_needed)))
-
 # Next, use the CPUID instruction to determine the processor type.
 
        OP(push,l)      REG(ebx)
@@ -464,28 +459,28 @@ i386_initialize_no_fp:
 
 # Detect "GenuineIntel".
 
-       OP(cmp,l)       TW(IMM(HEX(756e6547)),REG(ebx))
-       jne             not_intel_cpu
-       OP(cmp,l)       TW(IMM(HEX(49656e69)),REG(edx))
-       jne             not_intel_cpu
-       OP(cmp,l)       TW(IMM(HEX(6c65746e)),REG(ecx))
-       jne             not_intel_cpu
+#      OP(cmp,l)       TW(IMM(HEX(756e6547)),REG(ebx))
+#      jne             not_intel_cpu
+#      OP(cmp,l)       TW(IMM(HEX(49656e69)),REG(edx))
+#      jne             not_intel_cpu
+#      OP(cmp,l)       TW(IMM(HEX(6c65746e)),REG(ecx))
+#      jne             not_intel_cpu
 
 # For CPU families 4 (486), 5 (Pentium), or 6 (Pentium Pro, Pentium
 # II, Pentium III), don't use CPUID synchronization.
 
-       OP(mov,l)       TW(IMM(HEX(01)),REG(eax))
-       cpuid
-       OP(shr,l)       TW(IMM(HEX(08)),REG(eax))
-       OP(and,l)       TW(IMM(HEX(0000000F)),REG(eax))
-       OP(cmp,l)       TW(IMM(HEX(4)),REG(eax))
-       jl              done_setting_up_cpuid
-       OP(cmp,l)       TW(IMM(HEX(6)),REG(eax))
-       jg              done_setting_up_cpuid
-
-       jmp             cpuid_not_needed
-
-not_intel_cpu:
+#      OP(mov,l)       TW(IMM(HEX(01)),REG(eax))
+#      cpuid
+#      OP(shr,l)       TW(IMM(HEX(08)),REG(eax))
+#      OP(and,l)       TW(IMM(HEX(0000000F)),REG(eax))
+#      OP(cmp,l)       TW(IMM(HEX(4)),REG(eax))
+#      jl              done_setting_up_cpuid
+#      OP(cmp,l)       TW(IMM(HEX(6)),REG(eax))
+#      jg              done_setting_up_cpuid
+#
+#      jmp             cpuid_not_needed
+#
+#not_intel_cpu:
 
 # Detect "AuthenticAMD".
 
@@ -496,20 +491,24 @@ not_intel_cpu:
        OP(cmp,l)       TW(IMM(HEX(444d4163)),REG(ecx))
        jne             not_amd_cpu
 
-# For CPU families 4 (Am486, Am586) or 5 (K5, K6), don't use CPUID
-# synchronization.
+# Problem appears to exist only on Athlon models 1, 2, 3, and 4.
 
        OP(mov,l)       TW(IMM(HEX(01)),REG(eax))
        cpuid
+
+       OP(mov,l)       TW(REG(eax),REG(ecx))
        OP(shr,l)       TW(IMM(HEX(08)),REG(eax))
        OP(and,l)       TW(IMM(HEX(0000000F)),REG(eax))
-       OP(cmp,l)       TW(IMM(HEX(4)),REG(eax))
-       jl              done_setting_up_cpuid
-       OP(cmp,l)       TW(IMM(HEX(5)),REG(eax))
-       jg              done_setting_up_cpuid
+       OP(cmp,l)       TW(IMM(HEX(6)),REG(eax))        # family 6 = Athlon
+       jne             done_setting_up_cpuid
+
+       OP(mov,l)       TW(REG(ecx),REG(eax))
+       OP(shr,l)       TW(IMM(HEX(04)),REG(eax))
+       OP(and,l)       TW(IMM(HEX(0000000F)),REG(eax))
+       OP(cmp,l)       TW(IMM(HEX(6)),REG(eax))        # model 6 and up OK
+       jge             done_setting_up_cpuid
 
-cpuid_not_needed:
-       OP(mov,l)       TW(IMM(HEX(00000000)),ABS(EVR(ia32_cpuid_needed)))
+       OP(mov,l)       TW(IMM(HEX(00000001)),ABS(EVR(ia32_cpuid_needed)))
 
 not_amd_cpu:
 done_setting_up_cpuid: