Problems with serial and DHCP when booting from NFS

[lipeng at ict.ac.cn]

Hi all,

I am porting a MontaVista Linux for PPC405 and encountering some problems. I hope someone can help me find it out.

1. About the serial port. I have solved this problem, but I don't know why. If I set "Initial Kernel Command String" as "console=ttyS0,19200 ip=on nfsroot=[my_nfsroot] rw", after outputing "Now booting the kernel" in the booting process, the booting kernel seems hanging there. In fact, when I checked the log of DHCP server, I found the PPC had already sent DHCP requests. It can be infered that the kernel had been booted but serial had something wrong, so no other information was output after "Now booting the kernel". If I set "Initial Kernel Command String" as "ip=on nfsroot=[my_nfsroot] rw", the booting information will appear on the terminal window correctly after "Now booting the kernel". I don't know why. I use Uart Lite and the baud rate is 19200.

2. About the DHCP. The kernel is boot from NFS, so I enabled the DHCP. From the information on terminal window, I knew that DHCP requests were always time out and the client kept retrying. But when I checked the log of DHCP server, I found the server had already offered IP to the client kernel. It seems the client kernel has some problem to receive the DHCP offer, has anyone encountered similar problems? How to solve this problem?

Thanks.