[U-Boot] config: enable CONFIG_API in distro config

[Leif Lindholm]

On Fri, Apr 18, 2014 at 05:54:51PM -0500, Rob Herring wrote:
> > a) It was excruciatingly slow, to the point of not being useful.
> >
> > b) The binary had hard-coded memory layout, and hence couldn't be
> > generic across multiple boards, since SoCs put their RAM in different
> > places, boards have differing amounts of RAM, etc. This kinda defeats
> > the whole purpose, since distros would need to install board-specific
> > Grub binaries. Perhaps this could be solved similarly to the kernel's
> > CONFIG_ARM_PATCH_PHYS_VIRT?
> 
> Uggg, That certainly sounds pointless to use.
> 
> Leif, comments?

a)
As for speed, the u-boot grub used to run with caches disabled (default
mode for "kernel" image loaded by bootm). Vladimir got fed up just
before Christmas and changed that, so it's now fast even on the RPi..

b)
There is no real restriction on RAM size (other than you having enough),
but the link address is currently fixed at build time.
Optimally, the grub kernel should be position independent, but that
wasn't trivial, and by the time the basic port was upstream, Linaro
Enterprise Group had de-prioritised work on 32-bit ARM.

Ian Campbell wrote some neat patches for patching the (grub) kernel
link addres at grub-install time, which would be an improvement, but is
also quite invasive over several ports:
http://lists.gnu.org/archive/html/grub-devel/2013-12/msg00426.html

/
    Leif