[U-Boot-Users] pci memory booting on ppc460

[Wolfgang Denk]

In message <480E32A6.8080908 at ovro.caltech.edu> you wrote:
> 
...
> > from a flash?  We are developing our app with the canyonlands
> > board, but we won't be able to try the PCI boot until we have our
> > own board finished.
> 
> U-Boot is a bootloader. What you are describing here
> circumvents needing a bootloader.

This is not necessarily true. Ther emay be many reasons why you still
want to run a boot loader (like U-Boot) on  the  PCI  device's  local
processor.

> If you want to boot your board over PCI, then the board
> will most likely be a peripheral board (a host would need
> to boot and setup bridges, so you would have a hard time
> booting a host through a bridge that is not configured).
> The host CPU would hold the image of the kernel that you were
> planning to boot onto the PCI peripheral board. However,
> your host would need to perform all of the tasks normally
> performed by the bootloader; setup the memory map, memory
> controllers, and peripherals that Linux expects to find
> configured. Then even trickier, is to setup the kernel
> boot command line arguments and device tree. My guess would
> be that you would have to hardwire that info into your kernel
> image, or add a small bootloader to the kernel image to
> setup the arguments to the kernel proper.

You see? There is plenty of good reasons to have a well-known,
powerful boot loader available :-)

> Save yourself a lot of trouble, and no community support,

Who says "no community support"? This is a  perfectly  legal  way  of
using U-Boot, and we we can, we will help.


Best regards,

Wolfgang Denk

-- 
DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
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It is easier to change the specification to fit the program than vice
versa.