Bug 9066 - /proc/cpuinfo reports incorrect information for Via C3
/proc/cpuinfo reports incorrect information for Via C3
Status: RESOLVED OBSOLETE
Product: Platform Specific/Hardware
Classification: Unclassified
Component: i386
All Linux
: P1 normal
Assigned To: Rafael J. Wysocki
:
Depends on:
Blocks:
  Show dependency treegraph
 
Reported: 2007-09-25 09:43 UTC by Rolf Leggewie
Modified: 2012-09-19 13:47 UTC (History)
5 users (show)

See Also:
Kernel Version: 2.6.22
Tree: Mainline
Regression: No


Attachments

Description Rolf Leggewie 2007-09-25 09:43:55 UTC
This bug has also been reported as https://bugs.launchpad.net/ubuntu/+source/linux-source-2.6.20/+bug/119940 previously.

Most recent kernel where this bug did not occur: unknown, I believe 2.4.2x was still correct
Distribution: ubuntu gutsy
Hardware Environment: Via C3 processor

Problem Description:

The output of "cat /proc/cpuinfo" is wrong for the Via C3 processor.  It is being underreported by 33% of the true value.

processor : 0
vendor_id : CentaurHauls
cpu family : 6
model : 6
model name : VIA Samuel
stepping : 2
cpu MHz : 400.179
[...]

My CPU has 600 MHz.
Comment 1 Dave Jones 2007-09-25 09:57:14 UTC
your CPU also has speed scaling technology called longhaul.
It's scaled down to its lowest frequency.
Comment 2 Rolf Leggewie 2007-09-25 10:06:24 UTC
Thank you, Dave for the quick reply.

(In reply to comment #1)
> your CPU also has speed scaling technology called longhaul.
> It's scaled down to its lowest frequency.

I am afraid this unfortunately is incorrect.  CPU scaling actually is broken as well on this CPU.  But that is a separate issue, of course.  AFAIK, this CPU runs at 600 and 300 MHz, but never 400 MHz. I think I remember that when the scaling was still working that "cat/proc/cpuinfo" would claim the machine was running either at 400MHz under load and 200 MHz when idle, in both cases underreporting by 33%.  At any rate, the reported frequency never changes - even under high load - nowadays.
Comment 3 Natalie Protasevich 2007-12-12 14:36:59 UTC
Rolf, have you tried recent kernels? It's been quite a bit of updates on cpufreq since 2.6.20 anyway.
Comment 4 Rolf Leggewie 2007-12-17 15:47:59 UTC
Thanks, Natalie.  I will try to test out a more recent kernel as soon as possible.  Not really sure when that will be though.

Maybe some excerpt from dmesg after I upgraded to feisty is of help?  I will continue on to ubuntu gutsy later today.

# uname -a
Linux Rie 2.6.20-16-386 #2 Sun Sep 23 19:47:10 UTC 2007 i686 GNU/Linux

[  240.876877] longhaul: VIA C3 'Samuel' [C5A] CPU detected.  Longhaul v1 supported.
[  240.876946] ACPI Exception (utmutex-0263): AE_BAD_PARAMETER, Thread E33AEA70 could not acquire Mutex [2] [20060707]
[  240.877016] longhaul: No ACPI support. Unsupported northbridge.
[  241.273098] acpi_cpufreq: Unknown symbol acpi_processor_notify_smm
[  241.275066] acpi_cpufreq: Unknown symbol acpi_processor_unregister_performance
[  241.277387] acpi_cpufreq: Unknown symbol acpi_processor_preregister_performance
[  241.279238] acpi_cpufreq: Unknown symbol acpi_processor_register_performance
Comment 5 Rolf Leggewie 2008-01-15 02:56:20 UTC
Still the same on 2.6.22-14-386.  Maybe the information I just attached to https://bugs.launchpad.net/ubuntu/+source/linux-source-2.6.20/+bug/50431 could be interesting for this bug as well.  Feel free to ask for any further information. I'll happily provide it.
Comment 6 Thomas Gleixner 2008-09-05 05:29:31 UTC
Any updates on this one ?
Comment 7 Rolf Leggewie 2008-09-05 05:51:18 UTC
(In reply to comment #6)
> Any updates on this one ?

Unfortunately, no.  I have not gotten around to keep pace with recompiling a new kernel every time.  I am also reluctant to boot the machine too often.  I don't think this problem will just magically go away, though.  Somebody will actively have to push a fix.  Before that, we'd need to triage where this is coming from.  I'm looking for help and advise on that.
Comment 8 Thomas Gleixner 2008-09-12 06:57:32 UTC
[  240.876946] ACPI Exception (utmutex-0263): AE_BAD_PARAMETER, Thread E33AEA70
could not acquire Mutex [2] [20060707]
[  240.877016] longhaul: No ACPI support. Unsupported northbridge.

This problem is not in the kernel. The ACPI table of this system is not correct. w/o ACPI and an unknown northbridge there is not much to do. Can you please provide the output of lspci -nn ?
Comment 9 Rolf Leggewie 2008-09-17 01:27:48 UTC
Thomas, thank you for your support.  I hope you don't mind me adding you to the cc list.  Here is the information you requested.

$ lspci -nn
00:00.0 Host bridge [0600]: Silicon Integrated Systems [SiS] 620 Host [1039:0620] (rev 02)
00:00.1 IDE interface [0101]: Silicon Integrated Systems [SiS] 5513 [IDE] [1039:5513] (rev d0)
00:01.0 ISA bridge [0601]: Silicon Integrated Systems [SiS] SiS85C503/5513 (LPC Bridge) [1039:0008] (rev b3)
00:01.1 Unknown class [ff00]: Silicon Integrated Systems [SiS] ACPI [1039:0009]
00:01.2 USB Controller [0c03]: Silicon Integrated Systems [SiS] USB 1.1 Controller [1039:7001] (rev 11)
00:02.0 PCI bridge [0604]: Silicon Integrated Systems [SiS] Virtual PCI-to-PCI bridge (AGP) [1039:0001]
00:09.0 Multimedia controller [0480]: Philips Semiconductors TriMedia TM-1300 [1131:5402] (rev 82)
00:0a.0 Ethernet controller [0200]: Intel Corporation 82557/8/9/0/1 Ethernet Pro 100 [8086:1229] (rev 05)
00:0c.0 Multimedia audio controller [0401]: C-Media Electronics Inc CM8738 [13f6:0111] (rev 10)
01:00.0 VGA compatible controller [0300]: Silicon Integrated Systems [SiS] 530/620 PCI/AGP VGA Display Adapter [1039:6306] (rev 2a)
Comment 10 dolphs 2010-06-21 04:15:49 UTC
Hi - It has been a while this post got updated, I am not sure though if I should open a new bug though.
I compiled kernel 2.6.34 to my needs for the VIA Epia PX5000EG board. Unfortunately even with this kernel version I run at this stage in to a broken status of longhaul APIC. When this longhaul issue will be fixed for VIA platforms please? To be specific the exact error reported in dmesg: " longhaul: APIC detected. Longhaul is currently broken in this configuration ". 
The CPU runs as 500Mhz as it falls back to performance mode instead of ondemand:

cat /proc/cpuinfo
processor       : 0
vendor_id       : CentaurHauls
cpu family      : 6
model           : 13
model name      : VIA Eden Processor  500MHz
stepping        : 0
cpu MHz         : 500.000
cache size      : 128 KB
fdiv_bug        : no
hlt_bug         : no
f00f_bug        : no
coma_bug        : no
fpu             : yes
fpu_exception   : yes
cpuid level     : 1
wp              : yes
flags           : fpu vme de pse tsc msr pae mce apic sep mtrr pge cmov pat clflush acpi mmx fxsr sse sse2 pni est xtpr rng rng_en ace ace_en ace2 ace2_en phe phe_en pmm pmm_en
bogomips        : 999.55
clflush size    : 64
cache_alignment : 64
address sizes   : 36 bits physical, 32 bits virtual
power management:


lspci -nn
00:00.0 Host bridge [0600]: VIA Technologies, Inc. CX700/VX700 Host Bridge [1106:0324] (rev 10)
00:00.1 Host bridge [0600]: VIA Technologies, Inc. CX700/VX700 Host Bridge [1106:1324]
00:00.2 Host bridge [0600]: VIA Technologies, Inc. CX700/VX700 Host Bridge [1106:2324]
00:00.3 Host bridge [0600]: VIA Technologies, Inc. CX700/VX700 Host Bridge [1106:3324]
00:00.4 Host bridge [0600]: VIA Technologies, Inc. CX700/VX700 Host Bridge [1106:4324]
00:00.7 Host bridge [0600]: VIA Technologies, Inc. CX700/VX700 Host Bridge [1106:7324]
00:01.0 PCI bridge [0604]: VIA Technologies, Inc. VT8237/VX700 PCI Bridge [1106:b198]
00:0f.0 IDE interface [0101]: VIA Technologies, Inc. VX800 Serial ATA and EIDE Controller [1106:5324]
00:10.0 USB Controller [0c03]: VIA Technologies, Inc. VT82xxxxx UHCI USB 1.1 Controller [1106:3038] (rev 90)
00:10.1 USB Controller [0c03]: VIA Technologies, Inc. VT82xxxxx UHCI USB 1.1 Controller [1106:3038] (rev 90)
00:10.2 USB Controller [0c03]: VIA Technologies, Inc. VT82xxxxx UHCI USB 1.1 Controller [1106:3038] (rev 90)
00:10.4 USB Controller [0c03]: VIA Technologies, Inc. USB 2.0 [1106:3104] (rev 90)
00:11.0 ISA bridge [0601]: VIA Technologies, Inc. CX700/VX700 PCI to ISA Bridge [1106:8324]
00:11.7 Host bridge [0600]: VIA Technologies, Inc. CX700/VX700 Internal Module Bus [1106:324e]
00:13.0 Host bridge [0600]: VIA Technologies, Inc. CX700/VX700 Host Bridge [1106:324b]
00:13.1 PCI bridge [0604]: VIA Technologies, Inc. CX700/VX700 PCI to PCI Bridge [1106:324a]
01:00.0 VGA compatible controller [0300]: VIA Technologies, Inc. CX700/VX700 [S3 UniChrome Pro] [1106:3157] (rev 03)
02:06.0 Ethernet controller [0200]: VIA Technologies, Inc. VT6105/VT6106S [Rhine-III] [1106:3106] (rev 8b)
Comment 11 Rolf Leggewie 2012-09-19 13:47:02 UTC
So sad to see this ticket marked obsolete today.  I really like this machine.

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