CPU name for "pure" i386 missing

CPU name for "pure" i386 missing

[Cesar Eduardo Barros]

Looks like every time the CPU detection code is rewritten, the printing of the
CPU name for "pure" (i.e. "original") 386s suffer. Last time, the "\n" after
the "CPU: 386" line was missing.

This time it's worse. It's tripping the "unknown CPU" code path:

CPU: Before vendor init, caps: 00000000 00000000 00000000, vendor = 255
[...]
CPU: ff/00

and looking at /proc/cpuinfo:

processor       : 0
vendor_id       : unknown
cpu family      : 3
model           : 0
model name      : ff/00
stepping        : unknown
fdiv_bug        : no
hlt_bug         : no
f00f_bug        : no
coma_bug        : no
fpu             : no
fpu_exception   : no
cpuid level     : -1
wp              : no
flags           :
bogomips        : 3.62


Shouldn't the code be supposed to figure that, since there is no cpuid, it
should be a 386 or an early 486?

I think that table_lookup_model in arch/i386/kernel/setup.c should code a
vendor of 255 as a special case and return "386" or something like that instead
of bailing out. If everybody agrees, I'll make a patch for Linus.

-- 
Cesar Eduardo Barros
cesarb@nitnet.com.br
cesarb@dcc.ufrj.br

[PATCH] Re: CPU name for "pure" i386 missing

[Cesar Eduardo Barros]

I've made a patch to fix the problem. I've not even compiled it yet (I might do
it later).


--- linux-2.4.2.orig/arch/i386/kernel/setup.c	Tue Feb 27 10:17:18 2001
+++ linux-2.4.2/arch/i386/kernel/setup.c	Tue Feb 27 11:04:54 2001
@@ -1996,6 +1996,15 @@
 	case X86_VENDOR_UNKNOWN:
 	default:
 		/* Not much we can do here... */
+		/* Check if at least it has cpuid */
+		if (c->cpuid_level == -1)
+		{
+			/* No cpuid. It must be an ancient CPU */
+			if (c->x86 == 4)
+				strcpy(c->x86_model_id, "486");
+			else if (c->x86 == 3)
+				strcpy(c->x86_model_id, "386");
+		}
 		break;
 
 	case X86_VENDOR_CYRIX:

-- 
Cesar Eduardo Barros
cesarb@nitnet.com.br
cesarb@dcc.ufrj.br