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 at soneticom.com
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Frank Bennett
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