Enable UART4 in AST2500

mw 1e6e2000 1688a8a8

mw 1e6e200c e1c47e80

mw 1e78f00c 93

mw 1e78f00c 27 //Baudrate 38400 (divisor =13x3=39=27h)

mw 1e78f00c 13

mw 1e78f000 45 //output 'D'

[Linux]HZ, jiffies and tick

HZ: total timer interrupts per second.
tick: 1/HZ, the time for each timer interrupt.
jiffies: total ticks from Linux boot.

Do something after 1 second, e.g. kernel timer
jiffies + (1 second)/ticks = jiffies + HZ

[Linux]The OS Critical Stop sensor event.

http://openipmi.sourceforge.net/IPMI.txt

上述openipmi user guide有提到當panic timeout發生時，Openipmi可以送筆OS critical stop
event log給BMC。

Simple Linux Socket example

I would like to send the UDP packet carries the syslog payload.

#include the below head file
sys/socket.h
linux/sockios.h
fcntl.h
netdb.h
netinet/ether.h
netpacket/packet.h
net/if.h

The note for Linux shell

1. Iterate the member in the array
declare -a array

for i in "${arrar[@]}"
do
    echo $i
done

簡易DHCP server架設

In Ubuntu,

1. Configure the server IP as 192.168.1.254

2. Configure the default inteface
vi /etc/sysconfig/dhcpd
INTERFACES="eth3"

udhcpc in the Busybox

udhcpc [-Cfbnqtvo] [-c CID] [-V VCLS] [-H HOSTNAME] [-i INTERFACE]
[-p pidfile] [-r IP] [-s script] [-O dhcp-option]...