I have a custom embedded PowerPC board with no IDE devices. I just use
the 4MB flash SIMM and the 16MB DRAM. You have to write a bootloader
which sets up DRAM controllers and anyother peripherals needed. In my
case this is the ROM and RAM chipselects, clocks, watchdogs, console port
and some I/O port registers. My bootloader also has the ability to
program Motorola hex records (handling elf files would also be very
nice). I set a dipswitch when I want to program the flash. The
bootloader reads the dipswitch and waits for an hex stream via the
console. If the dipswitch is not set then it looks to see if any code is
loaded at a fixed location and jumps to that location if it does exist.
The linux kernel startup code then copies itself into DRAM, then
uncompresses it self into another part of DRAM, then executes the kernel.
The key is that you have to write your own bootloader to get things going
and the support programming the flash. I'm not an Intel person so I
don't know what the bios can offer you; probably everything but the flash
programming.
Brendan Simon.
Dave New wrote:
> That will vary wildly, depending on the Flash technology. The
> HOWTO's I found there seemed to cover what to do if you had
> a FLASH that emulated an IDE drive. Essentially just copy
> to the drive mounted temporarily as a slave device on the
> first IDE channel, make sure you have the boot pointers
> set up properly, then shutdown the system and change the
> drive over to primary and boot. Most of the other info
> is how to put together an initial ramdisk (initrd) image,
> etc., so that you can unpack an rootdisk image from the
> FLASH and run.
>
> My problem is that the particular board set I'm working
> with has a plain 'ol Flash part, with no particular
> support from the BIOS to make it look like a drive.
> The BIOS does know how to grab an image from the FLASH,
> dump it into memory, and jump to it, though. The
> trick is getting the stuff into the FLASH in the first
> place. I have some QNX utilities that we wrote to
> do this, but it's annoying (at best) to have to change
> a system over to booting from a QNX drive (or the
> QNX flash) only to FTP a new Linux kernel onto the
> system, to copy into the flash, only to have that
> one fail, reboot, retry, etc. ad infinitum.
>
> Right now, lack of available time to work this problem
> is really the only thing stopping me from wrestling
> this particular problem to the floor and besting it... 8-)
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