[U-Boot-Users] Re: FT u-boot shim

Kumar Gala
2006-04-27T19:40:42Z

On Apr 27, 2006, at 2:30 PM, Rune Torgersen wrote:

> Would it be possible to have the kernel smart enough that if it gets
> passed a bd_t pointer, it updates the dts before booting fully.
> Newer u-boot versions that support dts then would pass a NULL bd_t
> pointer to a kernel that supports dts. Kernel would then not update
> the
> dts, but use the one it gets handed.

What you are describing is the boot shim method.

U-boot is already capable of effectively doing this. You can set a u-
boot environment variable to make bootm do different things if you
have flat device tree support built into u-boot.

> bootm should be able to see if the kernel has an attached dts,
> update it
> with runtime parameters, and hand it off to the kernel. If it is an
> old
> kernel, hand it the bd_t pointer.

We can do this w/o too much modification to what is happening in u-
boot today. I'd probably like to keep the ability to build a dev
tree into the u-boot binary, but make the preferred means to pass a
blob into the bootm command.

- kumar