[U-Boot] ARM: vexpress: Extend default boot sequence to load script from MMC

[Jon Medhurst (Tixy) <jon.medhurst@linaro.org>]

On Tue, 2011-11-29 at 13:46 -0700, Tom Rini wrote:
> On Tue, Nov 29, 2011 at 6:46 AM, Jon Medhurst (Tixy)
> <jon.medhurst@linaro.org> wrote:
> > Extend the default boot sequence on Versatile Express to load a boot
> > script from MMC.
> >
> > Signed-off-by: Jon Medhurst <jon.medhurst@linaro.org>
> 
> Is there any interest in defining a common 'fancy' boot command?  Over
> on beagleboard (and a few other eval boards) we are (or will be)
> doing, roughly:
> Is there mmc? {
>   Can we load a bootscript? {
>     load it, do it
>   }
>   Can we load uEnv.txt? {
>     Did it set 'uenvcmd'? {
>       Run it
>     }
>   }
>   Did we load the kernel? {
>     bootm it
>   }
> }
> Try nand.
> 
> And it's not hard to replace NAND with "whatever flash the board sets"

It could make sense. However, the combinations of boot methods could get
quite big, e.g. do we include pxeboot, tftp?

If everything was included in the common 'fancy boot' then some boards
would have to define boot methods (or stubs) for things they weren't
interested in. And, conversely, if fancy boot didn't include everything,
then other people would need to extend it. 

I came across this issue with my patch. I wanted to look for a common
pattern to copy for my boot command. I was tempted by those which
included other options but then realised we didn't currently have a use
for them, and if I added them there would be more testing and
maintenance required.

So perhaps the number of boards interested in the common function would
be very small?

-- 
Tixy