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uCLinux Startup Code

Verfasst: 11.08.2006, 15:46:13
von Jagdish Bisawa

I have assembled & tested the LPC board by Ulrich. Now I want to download UcLinux onto it. After having followed the instructions found on this website & elsewhere, I could successfully build the image files with a crystal frequency of 12 MHz & PLL multiplier of 4.

However, nothing is working when I download the linux.bin & romfs.img files onto the board ( I cannot see anything on the Hyperterminal window ! ).

On further investigation, some questions came to my mind :

1) The head.S file in the source files contains machine startup code specific to the LPC22xx. On studying this code, I find that this code sets the PLL clock, VPB divider & also it configures remapping of interrupt vectors to External memory. Is the remapping correct ??? If we do a remapping of interrupt vectors to XRAM, then the vectors would be remapped to 0x80000000. We donot have any XRAM at this location on Ulrich's board !

2) This startup file also contains a couple of instructions like :
mov fp, #0
adr r5,LCO
Iam not sure if these are ARM instructions. Can somebody please guide as to what is happenning in these instructions

3) Is the head.S file that Iam referring to the right one to be used or is it that Ulrich has modified some part of this file to suit his board ?

4) Iam using my own boot loader that accepts the linux.bin over serial port & then copies it to the XRAM. After copying the files to XRAM, the bootloader jumps to the start of the location where the file was copied ( 0x81008000 ). Instead of copying from the MMC card, Iam copying from the Serial port of the LPC. I have tested some smaller applications by downloading in this manner & they all work. However, uClinux does not ?

Any help will be more than appreciated in this regard.

Jagdish Bisawa