[U-Boot] uImage load address and entry point with Minnowboard

[Wolfgang Denk]

Dear Vinoth,

In message <CAJst-kGA9s24O=BKa8ESWmtg-HgZ8oPC+i1h0BJWc0_c1uczrg at mail.gmail.com> you wrote:
> 
> 1) What's the address in the bootcmd corresponds to , I think it is

Define "bootcmd" - this can be anything.

> the address where we want the u-boot to load the Linux kernel image
> into RAM
> 
> For ex: fatload mmc 0:1 01000000 bzImage; zboot 01000000

This does not apply to your previous question.  We were talking about
the address entries in uImage files - but there you use a bzImage
which does not include the uImage header, and so it doesn not have any
"load address" or "entry point address" settings stored in the image.
Here you need to know these yourself.

> Here 01000000 is the address and bzImage is the compressed Linux
> kernel stored in mmc0 partition1. Once the Kernel is copied to RAM we
> are using zboot command to start the kernel, so after it Kernel
> unpacks itself and starts running

Correct - but this is a totally different scenario.

Note also that th enotation of "kernel unpacks itself" is dependent on
the image type and to some parts on the architecture.

> 2) I want to use uncompressed Kernel(vmlinux) instead of bzImage.
> U-boot directly doesn't support running vmlinux, so I need to generate
> the uImage using the mkImage tool. So the payload in my case in
> uncompressed kernel.  To generate this I want two addresses , load
> address and entry point address. You have mentioned that the addresses
> are often fixed. How can I get these addresses?

They are defined in the kerel build process; check Linux Makefiles,
and/or study the linker commands used when linking the kernel image.

> I am using the same address in bootcmd: fatload mmc 0:1 01000000
> uImage; bootm 01000000

In this case 0x01000000 is what I usually call the "download address",
i. e. the location where the uImage is stored in memory.  This has
nothing to do with the load address or entry pint address (except that
you will likely run into trouble if these should be the same or close
to it).

Best regards,

Wolfgang Denk

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