Bug 39845 - mtrr not working properly (kernel 2.4.2-2)
Summary: mtrr not working properly (kernel 2.4.2-2)
Alias: None
Product: Red Hat Linux
Classification: Retired
Component: kernel (Show other bugs)
(Show other bugs)
Version: 7.1
Hardware: i686 Linux
Target Milestone: ---
Assignee: Arjan van de Ven
QA Contact: Brock Organ
Depends On:
TreeView+ depends on / blocked
Reported: 2001-05-09 09:37 UTC by Bernhard Ege
Modified: 2007-04-18 16:33 UTC (History)
1 user (show)

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of:
Last Closed: 2001-05-14 12:20:02 UTC
Type: ---
Regression: ---
Mount Type: ---
Documentation: ---
Verified Versions:
Category: ---
oVirt Team: ---
RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: ---

Attachments (Terms of Use)

External Trackers
Tracker ID Priority Status Summary Last Updated
Red Hat Product Errata RHSA-2001:084 normal SHIPPED_LIVE Kernel: Kernel: 2001-06-21 04:00:00 UTC

Description Bernhard Ege 2001-05-09 09:37:03 UTC
From Bugzilla Helper:
User-Agent: Mozilla/4.77 [en] (X11; U; Linux 2.4.2-2 i686)

Description of problem:
I am using X 4.0.3 with nvidia 769 driver. I am using PCI mode. X was
running slower than on 2.2.16-22 kernel which made me look at /proc/mtrr:

reg00: base=0x00000000 (   0MB), size=16711936MB: write-back, count=1

This is obviously wrong. I can remove the entry and insert a correct one:

echo "disable=reg00" > /proc/mtrr
echo "base=0x00000000 size=0x10000000 type=write-back" > /proc/mtrr

/proc/mtrr has this to say:

reg00: base=0x00000000 (   0MB), size=16773376MB: write-back, count=1

I cannot enter further mtrr entries (I should be able to).

How reproducible:

Steps to Reproduce:
Any mtrr setting will be faulty, either entered using /proc/mtrr or letting
X (nvidia driver do it).

Additional info:

Here is what lspci says about my system (for better insight in my

00:00.0 Host bridge: Advanced Micro Devices [AMD] AMD-751 [Irongate] System
Controller (rev 23)
00:01.0 PCI bridge: Advanced Micro Devices [AMD] AMD-751 [Irongate] AGP
Bridge (rev 01)
00:07.0 ISA bridge: Advanced Micro Devices [AMD] AMD-756 [Viper] ISA (rev
00:07.1 IDE interface: Advanced Micro Devices [AMD] AMD-756 [Viper] IDE
(rev 03)00:07.3 Bridge: Advanced Micro Devices [AMD] AMD-756 [Viper] ACPI
(rev 03)
00:08.0 Multimedia audio controller: Yamaha Corporation YMF-724F [DS-1
Audio Controller] (rev 03)
00:0a.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL-8139 (rev
01:05.0 VGA compatible controller: nVidia Corporation NV11 (rev a1)

This is the MSI 6167 mainboard.

dmesg says this about mtrr (during bios initialisation):

mtrr: v1.37 (20001109) Richard Gooch (rgooch@atnf.csiro.au)
mtrr: detected mtrr type: Intel

dmesg has this to says about the later mtrr changes:

mtrr: type mismatch for d8000000,400000 old: write-back new:
NVRM: loading NVIDIA kernel module version 1.0-769
mtrr: type mismatch for d8000000,2000000 old: write-back new:

These two mtrr changes are the ones the nvidia kernel module issues
(they obviously fail).

Comment 1 Arjan van de Ven 2001-05-09 09:40:14 UTC
Please file all bugs regarding the binary-only NVidia driver to NVidia

Comment 2 Bernhard Ege 2001-05-09 10:35:37 UTC
This is *not* a nvidia related bug as it turns out it still exists when I shut
down X and unload the NVdriver module. I can empty the mtrr register:

echo "disable=reg00" > /proc/mtrr

/proc/mtrr is empty now and the system is *slow*.

I enter this to mtrr:

echo "base=0x00000000 size=0x10000000 type=write-back" > /proc/mtrr

/proc/mtrr now has this to say:

reg00: base=0x00000000 (   0MB), size=16773376MB: write-back, count=1

This is without any nvidia related binaries or anything else loaded.

Comment 3 Arjan van de Ven 2001-05-09 10:39:59 UTC
Please retry without the nvidia modules EVER being loaded since the reboot.

Comment 4 Bernhard Ege 2001-05-09 11:29:08 UTC
I have now performed a reboot and without ever having started the nvidia module
the problem still persists. This is what I did just after the reboot:

[root@overmind /root]# cat /proc/mtrr
reg00: base=0x00000000 (   0MB), size=16711936MB: write-back, count=1
[root@overmind /root]# echo "disable=reg00" > /proc/mtrr
[root@overmind /root]# echo "base=0x00000000 size=0x10000000 type=write-back" >
[root@overmind /root]# cat /proc/mtrr
reg00: base=0x00000000 (   0MB), size=16773376MB: write-back, count=1
[root@overmind /root]# lsmod
Module                  Size  Used by
nfsd                   69696   8  (autoclean)
lockd                  52464   1  (autoclean) [nfsd]
sunrpc                 61328   1  (autoclean) [nfsd lockd]
libafs-2.4.2-2        381264   2
autofs                 11264   2  (autoclean)
8139too                16480   1  (autoclean)
ipchains               38976   0  (unused)
ide-scsi                8352   0
scsi_mod               95104   1  [ide-scsi]
ide-cd                 26848   0
cdrom                  27232   0  [ide-cd]
nls_iso8859-1           2880   2  (autoclean)
nls_cp437               4384   2  (autoclean)
vfat                    9392   2  (autoclean)
fat                    32672   0  (autoclean) [vfat]

Any ideas?

Comment 5 Arjan van de Ven 2001-05-09 11:37:00 UTC
Is it correct that you have 256Mb of ram ?

Comment 6 Bernhard Ege 2001-05-09 12:00:31 UTC
Yes, that is correct.

Comment 7 Alexei Podtelezhnikov 2001-05-09 19:50:49 UTC
Sometimes, e.g. starting X, I see the same "mtrr: type mismatch" messages on 
Athlon MS-6195 motherboard (AMD-751/756) with Rage 128 pro AGP card. Do you need
more information?

Comment 8 Arjan van de Ven 2001-05-09 20:04:10 UTC
I just tried on my home athlon machine, and it works there. Although I have
768Mb of ram... This is a strange problem.

Comment 9 Bernhard Ege 2001-05-14 12:09:24 UTC
I have just installed the rawhide kernel, 2.4.3-2.14.14, rebooted and now MTRR
works as expected. Now alsasound cannot be recompiled
(/usr/src/linux-2.4.3/include/asm/pgalloc-2level.h is missing). kernel-headers
are also too old.

Comment 10 Arjan van de Ven 2001-05-14 12:19:57 UTC
"pgalloc-2level.h" is no longer present in the kernel. 
It is really surprising ALSA needs this header as it is a very very architecture
specific file and normal drivers shouldn't need to include it.
As this is a generic kernel change, I would not be surprised if a newer ALSA
driver is released that fixes this.

Comment 11 Bernhard Ege 2001-05-14 12:30:05 UTC
I forgot a make clean in alsasound and that caused the problem. alsasound works
just fine with kernel-2.4.3-2.14.14.

Comment 12 Nick Lamb 2001-05-27 23:03:58 UTC
This problem seems to have been a symptom of changes to the MTRR support in 2.4

The fix is mtrr.c version 1.39 which contains the comment

    20010312   Dave Jones <davej@suse.de>
               Ugh, I broke AMD support.
               Reworked fix by Troels Walsted Hansen <troels@thule.no>

This is included in 2.4.3 kernels from RawHide so all AMD users seeing errors
like this should probably consider upgrading.

Comment 13 Alexander Stohr 2001-06-01 01:38:20 UTC
This was an initialisation problem in the mtrr coding.
For current Athlon CPUs it was pretty likely that the
and/or mask values didnt get initialized and therfore
gigantic size values got composed from CPU registers.

The bug is fixed in official Linux Kernel 2.4.4 and later.

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