embedded linux help...

[Jason Gunthorpe]

On Wed, 30 Jun 1999, dony wrote:

>    I want to build embedded linux into FLASHROM . But I some questions
> to ask: 

I have been working on exactly this problem and then some for the past
little while. Hopefully I'll release a first draft of my stuff to the MTD
group sometime this week (http://www.linux-mtd.infradead.org/). 

>   1 After BIOS starts, how can it switch to FLASHROM address and load
> the linux kernel there? Do I have to write some BootLoader codes to load
> the kernel (similar to LILO)? If so, How should I begin to write? Can
> you give me some example codes or detailed hints? 

Yes, you will need to write a custom boot loader, when I left off work
Friday I had that doing everything but setting up the final bits to jump
to the kernel. The boot loader is structured as a bios extension and
modeled after the etherboot package - it boots directly from an image
stored in a FFS2 file system for which I have also written a R/W linux
driver for.. To make use it your flash has to map an 8k region of itself
into upper memory. 

>   2 After linux kernel starts, then how it find its root filesystem and
> mount it? Or can I remove the root file system and only let the kernel
> run? 

I've done two things in the past, the first is a simple compressed root
image and using the boot loader to bring that and the kernel into ram -
but that is not very good if you need to store state information, so my
latest focus has been to place a filesystem on the flash, using FFS2, a FS
designed specifically for flash.

Jason



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