fixing X for GeodeLX

[ link: fixing-x-for-geode-lx | tags: geode x linux x86emu ubuntu | updated: Wed, 30 Apr 2008 10:42:10 ]

Recently I have been doign a bit of contract work for Symbio Technologies. They have had me do various little projects part time. Most recently I got a chance to work on X.org video drivers for the Geode family.

Here is the progress...

  • starting X freezes the system

    With X-core release 1.3 (specifically Ubuntu/Gutsy, as that is what Symbio uses) there was a bug that caused a freeze of the system. This only occurred on some hardware, notably those systems with the GSW VGA BIOS.

    The first symptom that I could see was the freeze. I narrowed it down to X86EMU, an X subsystem that emulates the BIOS real-mode code in usermode to gain access to VGA BIOS features like monitor mode information (DDC). It turned out that the emulator was trying to write to an invalid I/O port, which disabled PIC interrupts.

    The first patch was triggered by a suggestion from Alan Cox that certain I/O ports are not to be touched from user space. These patches prevent X86EMU from accessing ports that Alan Cox said are not be accessed :)

    But why would the BIOS try to muck with the PIC when being asked for DDC info? Well it turned out that it wasn't. X86EMU choses not to allow drivers to access PCI directly, instead it goes through an emulation layer -- this is good -- but instead of emulating the access to arbitrary devices, it was always passing the requests to the VGA device that was in use by X -- this is bad. The BIOS was trying to read something from the PCI bridge, but X was returning values from the VGA device. The value was not validated, and caused PIC access.

    The second patch fixes the X86EMU PCI emulation bug. When the code emulated wants to talk to a certain device, instead of using the VGA device use what they asked for. The second patch here uses libpciaccess, while the first one does not.

    These patches were not yet picked up by upstream, but are in Ubuntu and possibly other distros.

    Ref: launchpad #140051 freedesktop #14332

  • switching back to virtual terminal doesn't work

    The problem here was in X86EMU again. The GSW VGA BIOS was issuing a CPUID instruction to perform some operation required for a VT-switch. The patch implements a CPUID instruction in X86EMU by returning raw values from the CPU, or the 486dx4 values on non-x86 processors.

    This patch was universally picked up by pretty much everyone because it's trivial.

    Ref: launchpad #180742

  • wide mode not working

    Next problem was a long time wish of the Geode users; to have wide monitors supported in native resolutions. The problem here was with the way that the resolutions are filtered by LXValidMode() against a table of valid modes. Something that is not required if the modes come from DDC and/or we are not using a PANEL (ie using a monitor connected by VGA cable).

    Jordan and I colaborated on this. In the end he produced a patch that I fixed a minor type-o bug in and tested...

    Ref: launchpad #197069

    Git: 1e763626a

    Packages in my Ubuntu PPA

If you have any questions about the above, give me a shout.

Bart's Blog

/fixing-x-for-geode-lx

About

I am an embedded Linux software developer and consultant operating under Jukie Networks Inc in Ottawa, Canada.

RSS Feed - Full Content

RSS Feed - Full Content

ipv6 ready

Valid XHTML 1.0 Transitional

Created with Vim

Created with Perl




Tags

abiword adam android apt asm ata audio bacula bash bios board-game boot bug busybox bzr c code conference debian debug desktop devel disk dns dpkg dream email embedded firefox font fs fun g1 gdb geode git git scm git-find git-graft go google gpg grub hardware html hw inkscape ion3 ipsec ipv6 ipv6summit.ca irc irssi joke kdb kernel klips kqemu kvm laptop lastfm ldap lighttpd linux lua lvm mail make mercurial meta mmc mouse-free mp3 mpd music mutt net nexusone nfs oclug ogre ols oom OOo openswan opteron osx ottawa perl photography power pxe qemu raid redhat rogers ruby sata sbc scm screen script scsi security sheeva shell skype spam squid ssd ssh suse svn tags talk thinkpad ubuntu uml unix urxvt usb uzbl vi video vim vimgit virt vpn vserver web weechat wifi wind wmii wmiirc-lua work x x86 x86emu xen xen-box-setup xfs xterm zsh

Posts

[ 20130409092758 ]
automount mmcblk devices

[ 20130316190507 ]
tunnelbroker vs IRC

[ 20110616180255 ]
HDD -> SDD

[ 20110517204617 ]
how to manually create a 6in4 tunnel

[ 20110501202915 ]
Presentation slides published!

[ 20110320190458 ]
What is IPv6, and why should I care?

[ 20110309230106 ]
Ottawa IPv6 Summit 2011

[ 20110309225149 ]
I am now an IPv6 Sage

[ 20101214145558 ]
It's a Holiday Miracle

[ 20101103095130 ]
ipv6 on your desktop in 2 steps

[ 20101020113026 ]
growing a live LVM volume

[ 20100915175649 ]
distributing DNS list through radvd

[ 20100908173402 ]
Canadian ipv6 drought

[ 20100903190623 ]
ipv6 certification

[ 20100723192259 ]
m4a to mp3

[ 20100723134522 ]
git 1.7.2 is out

[ 20100523092001 ]
console=ttyS0 with grub2

[ 20100426162644 ]
How many times is my function used within an executable?

[ 20100412100135 ]
vmlinux on Ubuntu

[ 20100328152951 ]
where your WIND coverage ends

[ 20100326113354 ]
Nexus One live in Ottawa on WIND Mobile

[ 20100311133411 ]
the WIND excitement

[ 20100302160743 ]
sata hotswap pico-HOWTO

[ 20100227093435 ]
serving http content out of a git repo

[ 20100225104049 ]
pimped out zsh prompt

[ 20100221184126 ]
live termcasting of your terminal over telnet

[ 20100215083725 ]
Debian on UBIFS upgrade on SheevaPlug

[ 20100214205532 ]
nexus one

[ 20100130150527 ]
skype on Debian Linux (64bit)

[ 20100125191021 ]
I am so peeved at Rogers

[ 20091205130455 ]
running really nice

[ 20091120225902 ]
notmuch for vim

[ 20091113102221 ]
squid and apt

[ 20091104195344 ]
using WIP branches to save every edit

[ 20091104194146 ]
using git workflows to avoid loosing intermediate changes

[ 20091019183503 ]
reflections on ACM Reflections

[ 20091013174248 ]
bacula rejected Hello command

[ 20091007235046 ]
pimping out git log

[ 20091002094400 ]
virtualization primer

[ 20090922110756 ]
adding an external encrypted volume under Debian

[ 20090905112529 ]
the dreaded process of rooting Rogers Dream

[ 20090830174551 ]
Cyanogen's recipe for Cupcake/Donut-like pastry

[ 20090827100232 ]
simpler android rooting

[ 20090821095427 ]
androids don't like water

[ 20090820215358 ]
prettier function tracing

[ 20090816151854 ]
Baking a cupcake

[ 20090814131559 ]
Hello Android!

[ 20090813100025 ]
sim unlocking a G1

[ 20090731185522 ]
rooting the droid

[ 20090727210307 ]
getting into android

[ 20090714094340 ]
importing an old project into git

[ 20090702113222 ]
Why pick Git?

[ 20090628131255 ]
select loop for X events

[ 20090625181315 ]
portable printf

[ 20090623225800 ]
switching to uzbl

[ 20090622223147 ]
Linux Symposium

[ 20090622214023 ]
bringing git-format-patch to bzr

[ 20090612215638 ]
nfs local caching with fscache and cachefilesd on Lenny

[ 20090610202041 ]
Scott Chacon smacks git around

[ 20090610150039 ]
how would you read a file into an array of lines

[ 20090609215141 ]
libguestfs

[ 20090609000208 ]
tiding up the PATH

[ 20090608232531 ]
only showing relevant messages in mutt by default

[ 20090608010405 ]
git-vim hacking

[ 20090530223801 ]
mark-yank-urls: fix bug allowing shell to interpret the url

[ 20090509212648 ]
wmiirc-lua v0.2.8 release

[ 20090509113125 ]
wmiirc-lua moving to github

[ 20090504101605 ]
two terminals one PWD

[ 20090501172645 ]
splitting files out of a commit

[ 20090409155905 ]
git workflow: git amend

[ 20090401112030 ]
how old are these files in git?

[ 20090330181138 ]
sles 11 on kvm

[ 20090323194942 ]
android true type font

[ 20090322203939 ]
popen with stdin, stdout, and stderr

[ 20090320214228 ]
shrinking URLs

[ 20090304004744 ]
readlater

[ 20081112150409 ]
splitting patches with git

[ 20081011081638 ]
creating busybox symlinks

[ 20081002215121 ]
wmiirc-lua v0.2.5 release

[ 20080916155113 ]
git-svn strangeness

[ 20080915112959 ]
installing git man pages quickly

[ 20080913112345 ]
wmiirc-lua v0.2.4 release

[ 20080825100454 ]
Kernel Walkthroughs - booting

[ 20080813210205 ]
Linux Kernel Booting

[ 20080719211329 ]
printable OLS/2008 schedule

[ 20080715214447 ]
wmiirc-lua updates

[ 20080713194704 ]
Git Screencast

[ 20080713143429 ]
four steps to reproducible Debian installs

[ 20080705150651 ]
USB2.0 enclosure benchmark

[ 20080703230924 ]
Linux Kernel Walkthroughs posted

[ 20080702113602 ]
Introducing the Ottawa Ruby folks to Git

[ 20080628160732 ]
Authenticating Linux against OSX LDAP directory

[ 20080627142123 ]
Canada Day Events 2008

[ 20080613162541 ]
Linux Kernel Walkthroughs

[ 20080510083828 ]
is my usb device connected to a fast port?

[ 20080509111534 ]
show more git info on zsh prompt

[ 20080430104202 ]
git-vim

[ 20080412100337 ]
color your word

[ 20080404105620 ]
show current git branch on zsh prompt (2)

[ 20080303200359 ]
how to track multiple svn branches in git

[ 20080301134220 ]
fixing X for GeodeLX

[ 20080108002540 ]
kvm nfs hang

[ 20080107160836 ]
screen -c relative path bug

[ 20080105132854 ]
WeeChat spell suggestions

[ 20071219221358 ]
show current git branch in zsh

[ 20071217141037 ]
wmiirc-lua kitchen sink repository

[ 20071212100316 ]
protecting sshd from OOM killer

[ 20071204234232 ]
wmiirc-lua v0.2.1 remembers a bit more

[ 20071013205336 ]
wmiirc-lua v0.2 has suspend and raw modes

[ 20070929112345 ]
wmiirc-lua debianization

[ 20070924104140 ]
zsh tip of the day - global aliases

[ 20070915094213 ]
wmiirc-lua v0.1.1

[ 20070913130838 ]
comparing two directories

[ 20070909204125 ]
git-rebase --interactive

[ 20070908115905 ]
zsh tab completion awesomeness

[ 20070902000736 ]
wmiirc in lua

[ 20070831150306 ]
debugging with -dbg libraries

[ 20070831142646 ]
svn status like output in git

[ 20070829141847 ]
Git Cheat Sheet

[ 20070821142038 ]
switching to abiword

[ 20070811105746 ]
forwarding ssh and X through screen

[ 20070807112531 ]
git-svnup

[ 20070724082355 ]
reducing power consumption

[ 20070722123734 ]
Makefile template

[ 20070722002649 ]
less, colourful

[ 20070719162359 ]
irssi docs

[ 20070716114553 ]
qemu eats up /dev/shm

[ 20070710214512 ]
git-clean in svn land

[ 20070705113139 ]
ipw2200 not working

[ 20070627191916 ]
git slides updated

[ 20070618220649 ]
unpopular debian packages on my system

[ 20070611125852 ]
git-svn with multiple branches

[ 20070517085321 ]
Linus on Git at Google

[ 20070510134551 ]
vim modelines insecure

[ 20070504205042 ]
bios disassembler

[ 20070504124124 ]
dd hex arguments

[ 20070503013555 ]
urxvt mouseless url yanking

[ 20070502211941 ]
gitdiff.vba v2

[ 20070419234350 ]
india

[ 20070418155857 ]
zsh fun

[ 20070418143632 ]
pipe to pastey.net

[ 20070418094151 ]
vimgrep alias

[ 20070416202545 ]
mouse-free

[ 20070406141850 ]
ATA messages via SCSI layer

[ 20070330221019 ]
GITDiff vim plugin

[ 20070329011735 ]
git presentation for OCLUG

[ 20070328123631 ]
fixing vim's [[ and ]] for bad code

[ 20070316092236 ]
pxeboot and nfsroot with debian

[ 20070312134706 ]
etc snapshots with git

[ 20070307004041 ]
remote power switch

[ 20070222215355 ]
klips-less openswan git tree

[ 20070221041316 ]
git caching for v1.5.x

[ 20070218002214 ]
klips loses zlib

[ 20070209172606 ]
vim and linux CodingStyle

[ 20070207205427 ]
my kqemu install

[ 20070204100100 ]
leaner meaner openswan

[ 20070115111917 ]
wmii+ruby xlock action

[ 20070112131252 ]
cloning xterms in wmii+ruby

[ 20070102010551 ]
wmii+ruby talk for OCLUG

[ 20061228220641 ]
dump and restore

[ 20061218100219 ]
C style

[ 20061101002027 ]
fetching all git branches from remote

[ 20061028111607 ]
local caching for git repos

[ 20061020145437 ]
automatic version creation with git

[ 20061018213306 ]
wmii w/ ruby wmiirc

[ 20061018201907 ]
small fonts

[ 20061007151802 ]
google-codesearch from vim

[ 20060928020813 ]
shell commands

[ 20060920093957 ]
letting screen apps use the ssh-agent

[ 20060908223613 ]
mpdscribble stream support

[ 20060907125149 ]
glGo on ubuntu/dapper amd64

[ 20060906163240 ]
lbdb and mutt

[ 20060902145643 ]
vim tutorial

[ 20060902135722 ]
fixing your terminal

[ 20060828124713 ]
apt-get pdiffs

[ 20060824224842 ]
256 colour xterms

[ 20060824152658 ]
dynamic IPcomp

[ 20060824145428 ]
inkscape++

[ 20060818150516 ]
tags/cscope for system headers

[ 20060805131557 ]
opteron 170, part 4

[ 20060805101941 ]
opteron 170, part 3

[ 20060803233234 ]
opteron 170, part 2

[ 20060802210126 ]
opteron 170

[ 20060729144129 ]
OLS keysigning / 2006

[ 20060728105500 ]
git-find findings

[ 20060727162941 ]
starting on git-find

[ 20060727113632 ]
git-graft and git-find brainstorm

[ 20060726224531 ]
pretty function tracing

[ 20060713174723 ]
uml and multiple network segments

[ 20060707182236 ]
lastfm artist and title to clipboard

[ 20060706162256 ]
reverting a git changeset

[ 20060629212003 ]
user #3

[ 20060628083456 ]
firefox crashes with form input

[ 20060621151402 ]
git vs hg

[ 20060612222204 ]
ldap account management

[ 20060612194523 ]
stupid ldap

[ 20060608092157 ]
rpm hell is right

[ 20060605095726 ]
OpenSSH VPNs

[ 20060604114317 ]
Lenovo lost a customer

[ 20060601234010 ]
generating html colourized sourcecode

[ 20060601211716 ]
ion3 greatness and acting on X selections

[ 20060526085644 ]
software RAID10 performance

[ 20060525234148 ]
learning to love git

[ 20060524121638 ]
recent vim7 articles

[ 20060516095748 ]
bootstrapping debian on my sbc

[ 20060428145140 ]
entropy injection

[ 20060423140628 ]
Adam

[ 20060414202507 ]
converting mp3s to CD

[ 20060413232836 ]
secure apt-get

[ 20060412194423 ]
xen domain0 on debian

[ 20060410220525 ]
LVM2 on RAID1 mirror

[ 20060410102824 ]
building a RHEL4 kernel w/ kdb support

[ 20060407230939 ]
xen on debian

[ 20060407230818 ]
Upgraded look

[ 20060330131334 ]
Flattered by a copy

[ 20060328165153 ]
vim7 from source

[ 20060308123539 ]
Perl, Catalyst, CPAN, and Debian

[ 20060308123302 ]
last.fm

[ 20060128124841 ]
carcassonne and zombies

[ 20060120135931 ]
Election Humour

[ 20050925130002 ]
ldap on debian

[ 20050528190034 ]
Error while mapping shared library sections

[ 20050124130158 ]
IRC over email gateway

[ 20050110225522 ]
brute force attacks sshd?

[ 20050108095026 ]
LDAP authentication (part 1)

[ 20041124130146 ]
sawfish workspace themes

[ 20041113082651 ]
Mini-DV to divx using mencoder

[ 20041004084525 ]
notes on vserver

[ 20040922104334 ]
fast kernel logging

[ 20040803104122 ]
Digital Rebel for sale... GONE

[ 20040714202912 ]
OpenOffice resources

[ 20040603175746 ]
photo editing

[ 20040601082817 ]
WRT54G

[ 20040503205227 ]
Digital Rebel

[ 20040420200136 ]
Open Office templates

[ 20040326082602 ]
bash vi editing mode

[ 20040315204142 ]
debian install CDs

[ 20040312155542 ]
change of jobs

[ 20040308091554 ]
spamassasin extras

[ 20040305163216 ]
cool debian tools

[ 20040305155708 ]
first post!




Bart Trojanowski
http://www.jukie.net/~bart
bart@jukie.net