We have built a simple instruction set simulator for the sparc v8 processor. The model consists of a v8 processor, a main memory and a character input and a character output device. Currently I am able to run simple user-level programs on this simulator which are built using a cross compiler and placed in the modeled main memory directly.
I am trying to get a linux kernel to run on this simulator by building a simplest bootloader. (I'm considering uClinux which is made for mmu-less systems). The uncompressed kernel and the filesystem are both assumed to be present in the main memory itself, and all that my bootloader has to do is pass the relevant information to the kernel and make a jump to the start of the kernel code. I have no experience in OS development or porting linux.
I have the following questions :
- What is this bare minimum information that a bootloader has to supply to the kernel ?
- How to pass this information?
- How to point the kernel to use my custom input/output devices?
There is some documentation available for porting linux to ARM boards, and from this documentation, it seems that the bootloader passes information about the size of RAM etc via a data structure called ATAGS. How is it done in the case of a Sparc processor? I could not find much documentation for Sparc on the internet. There exists a linux bootloader for the Leon3 implementation of Sparc v8, but I could not find the specific information I was looking for in its code.
I will be grateful for any links that explain the bare minimum information to be passed to a kernel and how to pass it. Thanks, -neha
