Clint Thomas wrote:

Hey guys,

I have gone through the Linuxppc embedded and dev lists for information related to what I am trying to do, but was unable to find exactly what i'm looking for.

Basically, the system I want linux running on does not require the initialization of hardware that U-boot provides, or at least it does not need it to boot the linux kernel. I want to load an uncompressed linux kernel into memory and start the execution of the kernel, without using any kind of bootloader. Is this possible? Or does linux need some kind of firmware or other software to tell it to start executing? Thanks for any info you might have.

You seem to be looking for a striped down U-boot functionality:
    o copy flash to ram and run code
but to do this:
    o processor registers need to be initilized
    o caches need to be flushed
    o interrupts need to be disabled
    o C environment (stack) needs to be setup
U-boot is fairly small compared to a x86 BIOS which has to find
multiple boot device choices, yet supports multiple architectures.

I'm using a BDI2000 to load/debug u-boot running in SDRAM
for a new PPC hardware design. U-boot is probably easier to
debug than the kernel!
U-boot has other features that help with initial H/W turnon:
    o it's a debug/monitor
          o ram test
          o ram/register read/modify
    o u-boot environment
          o IP address, mac address
          o Linux boot options - NFS verses flash
          o Ethernet/NFS option using a server enables:
             o debugging kernel changes
             o debugging kernel driver modules
             o quick change of application processes
             o cross compile target code on server to local target
             o telnet to embedded H/W
    o knows how to flash partitions
          o u-boot (/dev/mtd0) (well I use the BDI to flash here)
        o can flash kernel (/dev/mtd1)
          o can flash root fs (/dev/mtd2)
          o can flash config data (/dev/mtd3)
          o this partitioning will help with future F/W updates
          o kind of required if your flash is soldered to the board
          o to read/write flash requires u-boot to relocate itself to ram

Clinton Thomas
cthomas@soneticom.com

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