banias with different (unusual?) model_name

banias with different (unusual?) model_name

[matthias brill]

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hi jeremy

i've found a pentium-m banias which reports "Mobile Genuine Intel(R)
processor       1400MHz" in /proc/cpuinfo.  this (strange?) signature
prevents speedstep-centrino.c from working properly.

the machine is a asus L4000R-series (L4510RBP) pentium-m/ati9100igp
notebook.

"Enhanced SpeedStep" works as advertised for this particular pentium-m
with the following trivial patch applied:

# diff -up arch/i386/kernel/cpu/cpufreq/speedstep-centrino.c.default arch/i386/kernel/cpu/cpufreq/speedstep-centrino.c
--- arch/i386/kernel/cpu/cpufreq/speedstep-centrino.c.default	2004-08-19 19:53:59.000000000 +0200
+++ arch/i386/kernel/cpu/cpufreq/speedstep-centrino.c	2004-08-19 20:49:06.000000000 +0200
@@ -195,7 +195,7 @@ static struct cpufreq_frequency_table ba
 
 #define _BANIAS(cpuid, max, name)	\
 {	.cpu_id		= cpuid,	\
-	.model_name	= "Intel(R) Pentium(R) M processor " name "MHz", \
+	.model_name	= "Mobile Genuine Intel(R) processor       " name "MHz", \
 	.max_freq	= (max)*1000,	\
 	.op_points	= banias_##max,	\
 }

it seems that only the model_name is different for this CPU?

thias


# cat /proc/cpuinfo
processor	: 0
vendor_id	: GenuineIntel
cpu family	: 6
model		: 9
model name	: Mobile Genuine Intel(R) processor       1400MHz
stepping	: 5
cpu MHz		: 600.087
cache size	: 1024 KB
fdiv_bug	: no
hlt_bug		: no
f00f_bug	: no
coma_bug	: no
fpu		: yes
fpu_exception	: yes
cpuid level	: 2
wp		: yes
flags		: fpu vme de pse tsc msr mce cx8 apic sep mtrr pge mca cmov pat clflush dts acpi mmx fxsr sse sse2 tm pbe tm2 est
bogomips	: 1190.18

-- 
Matthias Brill <matthias.brill@akamail.com>

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Re: banias with different (unusual?) model_name

[Alan Cox]

On Gwe, 2004-08-20 at 10:33, matthias brill wrote:
> hi jeremy
> 
> i've found a pentium-m banias which reports "Mobile Genuine Intel(R)
> processor       1400MHz" in /proc/cpuinfo.  this (strange?) signature
> prevents speedstep-centrino.c from working properly.

Signatures appear to be BIOS set so that would make sense.


> # diff -up arch/i386/kernel/cpu/cpufreq/speedstep-centrino.c.default arch/i386/kernel/cpu/cpufreq/speedstep-centrino.c
> --- arch/i386/kernel/cpu/cpufreq/speedstep-centrino.c.default	2004-08-19 19:53:59.000000000 +0200
> +++ arch/i386/kernel/cpu/cpufreq/speedstep-centrino.c	2004-08-19 20:49:06.000000000 +0200
> @@ -195,7 +195,7 @@ static struct cpufreq_frequency_table ba
>  
>  #define _BANIAS(cpuid, max, name)	\
>  {	.cpu_id		= cpuid,	\
> -	.model_name	= "Intel(R) Pentium(R) M processor " name "MHz", \
> +	.model_name	= "Mobile Genuine Intel(R) processor       " name "MHz", \
>  	.max_freq	= (max)*1000,	\
>  	.op_points	= banias_##max,	\
>  }
> 

You need a new entry "_WEIRDBANIAS" and entries in the table so that
you don't break other people by such a change but yes

> it seems that only the model_name is different for this CPU?

Re: banias with different (unusual?) model_name

[Jeremy Fitzhardinge]

On Fri, 2004-08-20 at 11:33 +0200, matthias brill wrote:
> hi jeremy
> 
> i've found a pentium-m banias which reports "Mobile Genuine Intel(R)
> processor       1400MHz" in /proc/cpuinfo.  this (strange?) signature
> prevents speedstep-centrino.c from working properly.

Yeah, there seem to be a few of these around.  I'm just not certain that
they're identical to "normal" Banias as far as operating points go.

	J

Re: banias with different (unusual?) model_name

[matthias brill]

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hi alan, jeremy

On Fri, Aug 20, 2004 at 02:25:36PM +0100, Alan Cox wrote:
> > i've found a pentium-m banias which reports "Mobile Genuine Intel(R)
> > processor       1400MHz" in /proc/cpuinfo.  this (strange?) signature
> > prevents speedstep-centrino.c from working properly.
> 
> Signatures appear to be BIOS set so that would make sense.

that fact wasn't obvious to me -- i've updated the BIOS and the strange
banias signature is now gone.  it reports the expected "Intel(R)
Pentium(R) M processor 1400MHz" string now.

in excess the "ACPI-behaviour" changes from "totally broken" to "not
working" which is kind of a progress... 8-}


On Fri, Aug 20, 2004 at 07:19:31PM -0700, Jeremy Fitzhardinge wrote:
> Yeah, there seem to be a few of these around.  I'm just not certain that
> they're identical to "normal" Banias as far as operating points go.

it seems that the reported value depends on the mental health of the
BIOS-programmer at hand, therefore the suplied string might not be
trustworthy.

if i understand correctly, the type of the cpu can be determined by
looking at the family, model and stepping -- assuming that these values
are reported directly  by the CPUID (0FA2) instruction. 

the BIOS supplied model_name string in speedstep-centrino.c is parsed to
get the clock cycle time of the cpu.  is this actually supposed to be
the "right" way (or worse: the only way) to get this information?


thias

-- 
Matthias Brill <matthias.brill@akamail.com>

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Re: banias with different (unusual?) model_name

[Dave Jones]

On Sat, Aug 21, 2004 at 01:53:16PM +0200, matthias brill wrote:

 > if i understand correctly, the type of the cpu can be determined by
 > looking at the family, model and stepping -- assuming that these values
 > are reported directly  by the CPUID (0FA2) instruction. 

download the source for x86info sometime, and look at the hoops
it jumps through to determine what cpu its running on. It isn't
just as simple as a few cpuid calls any more. These days there are
typically up to a half dozen factors that you need to look at to
discriminate between possibilities. One of these, is cpu speed.
Unfortunatly, as we could have booted off mains, and hence a lower
clock speed, we can't do any runtime calculation like we do with
bogomips/jiffies, so we have to resort to looking at the model name
supplied by the BIOS.

 > the BIOS supplied model_name string in speedstep-centrino.c is parsed to
 > get the clock cycle time of the cpu.  is this actually supposed to be
 > the "right" way (or worse: the only way) to get this information?

It's pretty much all we have that we can trust.  If we could
do something else, I'd love to, as I distrust the abilities of
BIOS programmers as much as anyone else.

		Dave