Re: [patch-2.4.0-test12-pre3] microcode update for P4 (fwd)

Re: [patch-2.4.0-test12-pre3] microcode update for P4 (fwd)

[H. Peter Anvin]

Tigran Aivazian wrote:
> 
> On Sat, 2 Dec 2000, H. Peter Anvin wrote:
> >
> > OK, fair enough.  Let me make a new statement then: I suggest we preface
> > these with MSR_ anyway so we can tell what they really are.
> >
> 
> That is much better. Actually, I accept your suggestion. (because I have
> just found a few more cleanups to be done in the code but they were not
> worth a patch on their own but together with the above it is worth
> remaking the patch).
> 
> So, unless Linus already applied it I will resend a new one to him
> shortly.
> 
> Regards,
> Tigran
> 
> PS. Btw, the proof of my statement is found at:
> 
> http://developer.intel.com/design/pentium4/manuals/245472.htm
> 
> and download the PDF, then read the section 8.11.1 on page 8-32.

I believe you :)  Pardon me now, I have a foot to get unstuck from this
here mouth of mine...

	-hpa

-- 
<hpa@transmeta.com> at work, <hpa@zytor.com> in private!
"Unix gives you enough rope to shoot yourself in the foot."
http://www.zytor.com/~hpa/puzzle.txt
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[PATCH] setup.c cpuinfo flags notsc

[Hugh Dickins]

Peter,

Some minor mods to test12-pre5 (and earlier) arch/i386/kernel/setup.c:
please pass on to Linus if you approve.

1. Your "features" was reverted to "flags", but an extra tab is needed.

2. identify_cpu() re-evaluates x86_capability, which left cpu_has_tsc true
   (and cpu MHz shown as 0.000) in non-SMP "notsc" case: #ifdef CONFIG_TSC
   was bogus.  And set X86_CR4_TSD here when testing this cpu's capability,
   not where cpu_init() tests cpu_has_tsc (boot_cpu's adjusted capability).

I have removed the "FIX-HPA" comment line: of course, that's none of my
business, but if you approve the patch I imagine you'd want that to go too
(I agree it's a bit ugly there, but safest to disable cpu_has_tsc soonest).

Hugh

--- test12-pre5/arch/i386/kernel/setup.c	Tue Dec  5 17:25:55 2000
+++ linux/arch/i386/kernel/setup.c	Tue Dec  5 17:56:35 2000
@@ -1999,10 +1999,14 @@
 	 * we do "generic changes."
 	 */
 
+#ifndef CONFIG_X86_TSC
 	/* TSC disabled? */
-#ifdef CONFIG_TSC
-	if ( tsc_disable )
-		clear_bit(X86_FEATURE_TSC, &c->x86_capability);
+	if ( test_bit(X86_FEATURE_TSC, &c->x86_capability) ) {
+		if (tsc_disable || !cpu_has_tsc) {
+			clear_bit(X86_FEATURE_TSC, &c->x86_capability);
+			set_in_cr4(X86_CR4_TSD);
+		}
+	}
 #endif
 
 	/* Disable the PN if appropriate */
@@ -2172,7 +2176,7 @@
 			        "fpu_exception\t: %s\n"
 			        "cpuid level\t: %d\n"
 			        "wp\t\t: %s\n"
-			        "flags\t:",
+			        "flags\t\t:",
 			     c->fdiv_bug ? "yes" : "no",
 			     c->hlt_works_ok ? "no" : "yes",
 			     c->f00f_bug ? "yes" : "no",
@@ -2218,9 +2222,7 @@
 #ifndef CONFIG_X86_TSC
 	if (tsc_disable && cpu_has_tsc) {
 		printk("Disabling TSC...\n");
-		/**** FIX-HPA: DOES THIS REALLY BELONG HERE? ****/
 		clear_bit(X86_FEATURE_TSC, boot_cpu_data.x86_capability);
-		set_in_cr4(X86_CR4_TSD);
 	}
 #endif
 

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