u-boot dhcp request, no ack

In u-boot> dhcp

discover ->

offer <-

request ->

no ack!

discover, offer, request, loop...

While the same board can run dhcp client without problem in Linux.

It turns out that the problem is on dhcp server: some dhcp servers will ignore too fast request.

I found this fix to u-boot:

http://www.mail-archive.com/u-boot-users@lists.sourceforge.net/msg03276.html

Just put a short delay (50~100ms) between offer and request.

"route: SIOCDELRT: No such process"

"route: SIOCDELRT: No such process"

this message comes from "route del"

ref:
http://lists.busybox.net/pipermail/busybox/2010-December/074073.html

Invalid FAT entry (uboot)

Did you encounter

Invalid FAT entry

when using fatload or fatls command in uboot?
possibly the filesystem is corrupted (from the view of uboot).
For instance,

U-Boot > fatls mmc 0
2187544 uimage
Invalid FAT entry

1 file(s), 0 dir(s)

Try to format the partition to fat. (mkfs.vfat)
Copy origin files into it and try again.

bash, convert integer to ascii char

# convert integer to ascii char

chr() {

printf \\$(printf '%03o' $1)

}

for example,

echo `chr 0x61` ---> a

Ref:

http://ubuntuforums.org/showthread.php?t=735140

get free memory size in kernel

Just paste this section to where you want to check:

{

#define K(x) ((x) << (PAGE_SHIFT - 10))

struct sysinfo si; \

si_meminfo(&si); \

printk("free=%lu k\n", K(si.freeram)); \

}

may need to include linux/mm.h

Use vim/cscope/ctags to navigate linux kernel

Install cscope:

sudo apt-get install cscope exuberant-ctags

Generate cscope and ctag file for x86:

##################################

#!/bin/bash

# File name: genctags.sh

# Usage: genctags.sh x86

LNX=.

ARCH=x86

if [ ! -z "$1" ];then

ARCH="$1"

fi

if [ "$2" != "tag" ];then

echo "Gen cscope file for $ARCH ..."

find $LNX \

-path "$LNX/arch/*" ! -path "$LNX/arch/$ARCH*" -prune -o \

-path "$LNX/include/asm-*" ! -path "$LNX/include/asm-$ARCH*" -prune -o \

-path "$LNX/tmp*" -prune -o \

-path "$LNX/Documentation*" -prune -o \

-path "$LNX/scripts*" -prune -o \

-path "$LNX/drivers*" -prune -o \

-name "*.[chxsS]" -print > cscope.files

cscope -b -q -k

fi

echo "Gen ctags file ($ARCH)..."

EXCLUDE_PATH=`find . -path "$LNX/arch/*" ! -path "$LNX/arch/$ARCH*" -prune`

EXCLUDE_PATH2=

for path in $EXCLUDE_PATH

do

EXCLUDE_PATH2="$EXCLUDE_PATH2 --exclude=$path"

done

ctags -R $EXCLUDE_PATH2

###############################################

For vim:

Download http://cscope.sourceforge.net/cscope_maps.vim to ~/.vim/plugin/

try it:

vim ./init/main.c

move the cursor to a symbol then...

ctrl + ] -- goto definition

[ + d -- show macro definition (if it is a macro)

ctrl + o -- goto previous position

ctrl + i -- goto next position

ctrl + \ s -- list usages

ctrl + shift + space -- list usages and pops a select to a new window (ctrl+w o to close)

search tag "main":

: ta main

search tags including "main":

:ta /main

search tags beginning with "main":

:ta /^main

Ref:

http://adrianhuang.blogspot.com/2007/09/trace-code-gvimctagscscope.html

http://cscope.sourceforge.net/large_projects.html

http://cscope.sourceforge.net/cscope_vim_tutorial.html

http://tnerual.eriogerg.free.fr/vimqrc.html

http://www.thegeekstuff.com/2009/04/ctags-taglist-vi-vim-editor-as-sourece-code-browser/

enable svn diff color

> sudo apt-get install colordiff

> vim ~/.subversion/config

[helpers]

diff-cmd = colordiff

Ref:

COLOR-HIGHLIGHTED SVN DIFF OUTPUT