To change the default font of GTK application (such as Firefox). Create/Edit the file .gtkrc-2.0 in your home directory and insert the following line:

gtk-font-name="sans-serif 16"

When trying to use Xilinx CLKDLL, I had trouble using the DLLIOB to connect to the CLKFB input of the CLKDLL. I had this error when mapping was reached:

	ERROR:LIT:54 - IPAD symbol "CLKFB" driving IBUFG->CLKDLL is LOCed to a generic

	IOB site. It must be LOCed to a GCLKIOB site.

The problem came from the synthesis tool (XST) which automatically instanciated a IBUFG from IOB to the CLKFB pin of the CLKDLL. This is controlled by the "Add I/O Buffers" of "Xilinx Specific option" of XST in ISE. To prevent this but still allowing XST to add I/O buffers where needed,  i just added in my VHDL:

	ATTRIBUTE clock_buffer: string;

	ATTRIBUTE clock_buffer OF CLKFB: SIGNAL IS "none";

When using Xilinx Platform Studio (XPS) of the Embedded Development Kit (EDK), I create a custom component that instanciates a CLKDLL. When using it on the top level I had to tweak the synthesis script and added the a constraint file. In synthesis/<toplevel>_xst.scr file I add a line:

	-uc <toplevel>.xcf

and created the file <toplevel>.xcf with this content:

	BEGIN MODEL "system"
	    NET "sdram_clk_fb_pin" clock_buffer=ibuf;
	END;

This way XST puts an IBUF instead of an IBUFG.

Displaying  X applications when using sudo or su :

The problem: X security prevents another user from connecting to your X display. When you use sudo (or su) you effectively change your UID. A simple bypass would be to use "xhost +" to disable access control, but if you using a ssh tunneled session it doesn't work (don't ask me why). Instead you can fix the sudo config file to point XAUTHORITY variable to your user's ~/.Xauthority file. If like me your homes are NFS mounted, you might not have access to the users ~/.Xauthority file. So the solution is to do the following:
1. Find the magic cookie:

xauth list

and find the line that corresponds to your current display (echo $DISPLAY) eg:

lapsrv.epfl.ch/unix:10  MIT-MAGIC-COOKIE-1  24eadb1f0dfb9f48dfadb43a1541bd66

2. become the intended user:

sudo -s -u user

3. add magic cookie

xauth add displayname protocolname hexkey

In our case:

xauth add lapsrv.epfl.ch/unix:10 MIT-MAGIC-COOKIE-1  24eadb1f0dfb9f48dfadb43a1541bd66

Had some trouble launching Synplify Pro under linux with an error like:

symbol __pthread_atfork, version
GLIBC_2.0 not defined in file libpthread.so.0 with link time reference

I found someone had the same problem with another app. The trick here is to create a bogus library that provides __pthread_atfork function. I put a copy of the source locally.

Xilinx Impact uses Jungo drivers for USB and parallel port access. I had troubles with these drivers on my parallel ports as sometimes they just don't work. Michael Gernoth wrote a replacement library which works beautifully for the parallel port. You can get the source here (tarball).

Multimedia keys are a pain with linux and KDE. I have a Logitech keyboard with a few multimedia keys. I was interested to use the vol up/down/mute keys. In the KDE control center -> Regional & Accessibility -> Keyboard Layout  I set keyboard model to Logitech Access, but funny enough Mute and VolDown work but not VolUp. The problem lies in the setxkbmap files (in /usr/share/X11/xkb under FC7). In the file /usr/share/X11/xkb/symbols/inet

xkb_symbols "logitech_base" {

...

key <I2F> { [ XF86AudioRaiseVolume ] };

key <I30> { [ XF86AudioRaiseVolume ] };

The first of the two XF86AudioRaiseVolume lines is incriminated in my case. I just commented it out. And my VolUp key works.

If your not using a fancy window manager like KDE and still want to switch keyboard layout you can use the following script:

#!/bin/bash
LAYOUT1="setxkbmap -model logiik -layout us -variant intl"
LAYOUT2="setxkbmap -model logiik -layout fr_CH -variant basic"
TMPFILE="$HOME/.togglexkbmap.tmp"

if [ -f $TMPFILE ] 
then
    $LAYOUT1
    rm $TMPFILE
else
    $LAYOUT2
    touch $TMPFILE
fi

I put in ~/bin/togglexkbmap. You can then configure your wm to call this script on some key shortcut (Ctrl-Alt-K for eg).

Xilinx chipscope 9.1i install has problems connecting to the cable? You might not have TCL installed first and then when you try running cs_server.sh it replies with problems related to the init.tcl file not found. This file is found in $CHIPSCOPE/xilinx/bin/lib/tcl8.4/

What you have to do is to make a symbolic link in this way:
cd $CHIPSCOPE/bin ln -s ../xilinx/bin/lib .