[debian] disable pc beeper

Just append one line to /etc/modprobe.d/blacklist :


> echo "blacklist pcspkr" >> /etc/modprobe.d/blacklist


> reboot


Ref:
http://arsgeek.hubpages.com/hub/How-to-turn-off-the-annoying-system-beep-in-linux-DebianUbuntu

[debian] How to move /etc into ramfs easily

> vi /etc/init.d/rcS

Add these lines before "exec /etc/init.d/rc S":

echo "* Initialize RAM /etc..."
[ ! -d /etc-model ] && mkdir /etc-model
mount --rbind /etc /etc-model
mount -n -t tmpfs none /etc
cp -a /etc-model/* /etc/

> vi /etc-model/init.d/umountfs

Add "/etc" in the line:
case "$MTPT" in |/proc|/dev/|..........|/etc)

基本上它運作的邏輯是: 開機時, rcS會自動把 /etc 掛成RAM，然後把舊的 /etc (位在/etc-model)給copy進來。

所以之後要手動改系統預設的設定，都是要改 /etc-model 底下的。

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.