Between Linux and Anime

Okay, I’m gonna post this in here once and for all, if for nothing more than my own recording purposes. So the somewhat sticky problem of multiple-monitor configuration is getting very nice and shiny new GUI’s in Linuxland nowadays. KDE Plasma 4.6, for example, has something like this:

Very lovely. The vexing thing however is that it doesn’t have “full control” so to speak. It’s likely a xrandr frontend, and that’s all nice and good except that if your Xorg config isn’t set up right, no configuration actually works, except for cloning, which clearly isn’t the most useful set up around. It turns out that you need to set the maximum virtual screen size to a value larger than required for your set up. For example if you’re configuring a 1280×800 desktop and a 1440×900 desktop side-by-side, you’ll need a virtual screen size of at least 2720(1280 + 1440)x900, and if they’re stacked vertically you need at least 1440×1700(900+800). How do you set the virtual screen size? Open /etc/X11/xorg.conf in your favorite editor as root:

sudo nano /etc/X11/xorg.conf

And under the “Display” subsection of the “Screen” section, add a “Virtual” line with your desired virtual screen dimensions as arguments. Example:

Section "Screen"
	Identifier "aticonfig-Screen[0]-0"
	Device     "aticonfig-Device[0]-0"
	Monitor    "aticonfig-Monitor[0]-0"
	DefaultDepth     24
	SubSection "Display"
		Viewport   0 0
		Depth     24
		Virtual		3000 3000 # <-- ADD THIS LINE!
	EndSubSection
EndSection

And you should now be able to configure your multi-head set up with xrandr or with your preferred graphical frontend (in KDE Plasma 4.6 the frontend is at System Settings > Display and Monitor > Size and Orientation).

You know what the worst thing is? Software updates sometimes rebuild your Xorg.conf, overwriting your changes, which means that you may need to repeat the above again after certain updates. That’s what just happened to me, so I’d keep this page (or whatever other page on this problem you find) bookmarked.

And Linux has now officially taken over my new laptop :) I decided to try out installing the OpenSUSE-based KDE Four Live image (downloadable here), and it looks great so far! More importantly, I bought this laptop (HP G42 or something) well-knowing that it didn’t have Linux-friendly hardware. Well, it was relatively cheap and had great CPU and graphical specs (damn you Starcraft 2), plus the chaps manning the store were really nice.. Anyway, so I rolled my sleeves and set out to set myself up a Linux installation today expecting to spend some gruelling hours wrestling the inevitable issues – and was pleasantly surprised to have now apparently resolved everything quite cleanly and painlessly. Awesome :) And with that, I’m gonna pen me some trusty ol howto posts – the first ones in quite awhile I believe.

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I had to Google hard for this – twice, because I was too busy to blog this when I solved it the first time. Anyway, people not accustomed to sysadmin-ing on Fedora will find themselves quickly acquainted with this rather unfriendly beast called SELinux, which firmly prevents you from doing a bunch of stuff – sometimes quietly.

Anyway, it turns out that although sendmail is installed and working on Fedora by default, SELinux will by default prevent httpd (and thus your PHP scripts) from using it to send email. To fix this, simply tell SELinux to don’t do that, like so:

$ restorecon /usr/sbin/sendmail.sendmail
$ setsebool -P httpd_can_sendmail 1

Or, if you prefer, look for the httpd_can_sendmail boolean in the SELinux configuration GUI and tick it off. Restart httpd after that:

/etc/init.d/httpd restart

Source

For those of you folks out there who, like me, carry around an Ubuntu-based live CD/USB as a friendly and handy system recovery companion, you might be surprised and shocked (as I was) to discover that LVM partitions that some Fedora systems are apparently installed on are unsupported by stock Ubuntu live systems. Ie – you cannot mount these partitions or do anything with them except delete/format them.

Fortunately it turns out that there is a quick remedy – install that support. Make sure that you have internet access, then simply do:

sudo apt-get install lvm2

You should now be able to mount and read the partition.

Was a little disappointed that chinese subtitles don’t work out-the-box on mplayer. Well, ass ones seem to work fine, but srt ones don’t work at all and I had to Google it. Anyway, assuming you already have fonts that can display chinese characters, you can get mplayer to play chinese subs by giving it the parameter -subcp cp936.

mplayer -subcp cp936 your.moviefile

Edit: -subcp enca:zh:BIG5 also works, and seems to work better in some cases:

mplayer -subcp enca:zh:BIG5 your.moviefile

(thanks to Kees in the comments)

You can also use the -font option to manually specify a font that mplayer should use. Source.

If you’re on OpenSUSE and your X server refuses to start on boot, and stays blank on manual startx, spitting out errors that look like this:

symbol lookup error: /usr/lib64/libXi.so.6: undefined symbol: XESetWireToEventCookie

You’ve probably been a bad boy/girl and have been playing with non-standard Xorg drivers and repositories haven’t you :P Here’s what you can try on the terminal (since that’s all you’d have if X refuses to start): Symlink libXi.so.6 to libXi.so.6.0.0 instead of libXi.so.6.1.0 in /usr/lib, or /usr/lib64 on 64 bit systems.

# cd /usr/lib
# rm libXi.so.6
# ln -s libXi.so.6.0.0 libXi.so.6

That should hopefully let you startx, where you should probably proceed to remove the libXi package from Yast – as well as every other non-standard package you installed :) Source here.

Btw, yes this happened to me, and I was frantic. I’m reasonably comfortable on the console but as long as my DE wouldn’t start neither would my networkmanager, which means I had no internet – and which means my package manager commands were useless! Playing with Xorg drivers bit me hard that time. Srs bsns, it is. As someone wisely said in the source thread, “For the next time: adding experimental repos brings you in a world where you’re on your own, and where things like you’ve met now, easily happen.”