Bug 97402 – mtrr gone wacko on 2.6.12 kernels

• Product: Gentoo Linux
• Status: RESOLVED UPSTREAM

[Description Perry Lu 2005-06-29 09:28:53 UTC]

after upgrading from gentoo-sources-2.6.11-r11 to gentoo-sources-2.6.12-r1,
everything appears fine, but I was getting a peculiar msg on my kernel log: 
"mtrr: type mismatch for e0000000,100000 old: write-back new: write-combining"
first I thought it's just a warning, after checking /proc/mtrr I noticed
something wrong:

on my old kernel, /proc/mtrr looks like this:
reg00: base=0x00000000 (   0MB), size=1024MB: write-back, count=1
reg01: base=0xe8000000 (3712MB), size= 128MB: write-combining, count=1
reg02: base=0xf8000000 (3968MB), size=  64MB: write-combining, count=1
after upgrading to 2.6.12, it looks like this:
reg00: base=0x00000000 (   0MB), size=984064MB: write-back, count=1

screen refreshing was especially slow(e.g. ls -R /). I first thought it's a
problem with framebuffer, but after disabling it, all problem persists.

I experiencing the same problem on other 2.6.12 kernels as well(namely
ck-sources, mm-sources).

Reproducible: Always
Steps to Reproduce:
1.upgrade to 2.6.12 kernel
2.cat /proc/mtrr
3.




Portage 2.0.51.19 (default-linux/x86/2005.0, gcc-3.3.5-20050130,
glibc-2.3.4.20041102-r1, 2.6.11-gentoo-r11 i686)
=================================================================
System uname: 2.6.11-gentoo-r11 i686 Intel(R) Pentium(R) 4 CPU 2.80GHz
Gentoo Base System version 1.6.12
Python:              dev-lang/python-2.3.5 [2.3.5 (#1, Jun 16 2005, 05:33:57)]
ccache version 2.3 [enabled]
dev-lang/python:     2.3.5
sys-apps/sandbox:    1.2.9
sys-devel/autoconf:  2.59-r6, 2.13
sys-devel/automake:  1.7.9-r1, 1.8.5-r3, 1.5, 1.4_p6, 1.6.3, 1.9.5
sys-devel/binutils:  2.15.92.0.2-r10
sys-devel/libtool:   1.5.16
virtual/os-headers:  2.6.8.1-r2
ACCEPT_KEYWORDS="x86"
AUTOCLEAN="yes"
CFLAGS="-O2 -march=prescott -fomit-frame-pointer -pipe"
CHOST="i686-pc-linux-gnu"
CONFIG_PROTECT="/etc /usr/kde/2/share/config /usr/kde/3/share/config
/usr/lib/X11/xkb /usr/share/config /usr/share/texmf/dvipdfm/config/
/usr/share/texmf/dvips/config/ /usr/share/texmf/tex/generic/config/
/usr/share/texmf/tex/platex/config/ /usr/share/texmf/xdvi/ /var/qmail/control"
CONFIG_PROTECT_MASK="/etc/gconf /etc/terminfo /etc/env.d"
CXXFLAGS="-O2 -march=prescott -fomit-frame-pointer -pipe"
DISTDIR="/usr/portage/distfiles"
FEATURES="autoaddcvs autoconfig ccache digest distlocks fixpackages sandbox
sfperms strict"
GENTOO_MIRRORS="http://distfiles.gentoo.org
http://distro.ibiblio.org/pub/Linux/distributions/gentoo"
LANG="en_CA.utf8"
LDFLAGS="-Wl,-O1"
LINGUAS="en ja zh_CN zh_TW"
MAKEOPTS="-j3"
PKGDIR="/usr/portage/packages"
PORTAGE_TMPDIR="/var/tmp"
PORTDIR="/usr/portage"
PORTDIR_OVERLAY="/usr/local/portagejp /usr/local/portage"
SYNC="rsync://rsync.gentoo.org/gentoo-portage"
USE="x86 16bit X a52 aac aalib acpi alsa avi berkdb cairo ccache cdr cjk crypt
cups curl dga dhcp directfb divx4linux dvd dvdr emboss encode fam firefox flac
font-server fortran gdbm gif gimp gimpprint gnome gpm gstreamer gtk gtk2 gtkhtml
hal imagemagick imlib ipv6 java jpeg ldap libg++ libwww lm_sensors mad maildir
matroska mikmod mime mmx mono motif mp3 mpeg mplayer mysql ncurses nfs nls nptl
nvidia ogg oggvorbis opengl pam pdflib perl png posix python quicktime readline
real rtc samba sdl slang spell sse sse2 ssl svga tcltk tcpd tetex theora tiff
truetype truetype-fonts type1-fonts unicode usb userlocales v4l vorbis
win32codecs xine xinetd xml xml2 xmms xprint xscreensaver xv xvid zlib
linguas_en linguas_ja linguas_zh_CN linguas_zh_TW userland_GNU kernel_linux
elibc_glibc"
Unset:  ASFLAGS, CBUILD, CTARGET, LC_ALL

[Comment 1 Perry Lu 2005-06-29 09:32:05 UTC]

a little correction, after disabling framebuffer, the msg on my kernel log was
gone("mtrr: type mismatch for e0000000,100000 old: write-back new:
write-combining"), but all other problem persisted(slow screen refreshing, wacko
/proc/mtrr).

[Comment 2 Daniel Drake (RETIRED) 2005-06-30 03:54:16 UTC]

Does that message appear more than once?
When you say screen refreshing is slow, do you mean console only, or also in X?

Please try this patch:

http://lkml.org/lkml/2005/6/21/403

If that doesn't help, it would also be useful if you could test
vanilla-sources-2.6.13_rc1.

[Comment 3 Perry Lu 2005-06-30 05:39:45 UTC]

screen refreshing is slow on both console and X.

I have disabled vesafb, the problem persisted.

[Comment 4 Daniel Drake (RETIRED) 2005-07-05 11:58:16 UTC]

Any progress on the rest of the things I mentioned? Here they are again...

Does that message appear more than once?

Please try this patch:

http://lkml.org/lkml/2005/6/21/403

If that doesn't help, it would also be useful if you could test
vanilla-sources-2.6.13_rc1.

[Comment 5 Perry Lu 2005-07-05 13:20:12 UTC]

the problem persists after I patched the kernel(since I dont even have vesafb
support on my kernel).

I'm yet to try the new vanilla-source, since I wasn't able to find the proper
reiser4 patch for it(one of my partitions uses reiser4), the old reiser4 patch
wouldn't compile.

[Comment 6 Daniel Drake (RETIRED) 2005-07-07 15:43:51 UTC]

As long as your root isn't reiser4, it should be possible just to boot and check
the mtrr table, right? :)

This is an upstream bug, so if you could report it at http://bugzilla.kernel.org
and post the new bug URL here it would be appreciated. Testing 2.6.13-rc2 would
be useful, but is not required (unless they ask).

Thanks.