[U-Boot] [PATCH] allow config_distro_bootcmd to pass uuid to extlinux.conf

[Stephen Warren <swarren@nvidia.com>]

On 12/14/2014 07:52 AM, Iain Paton wrote:
> Set ptuuid and fsuuid variables to the partition / filesystem
> where we found extlinux.conf which allows us to use a replaceable
> parameter in the append line in extlinux.conf like this
> 
> append root=PARTUUID=${ptuuid}
> 
> this means we never have to hardcode a root=/dev/mmcblk0p1 type path
> anywhere.

Wouldn't the distro/... that creates extlinux.conf simply put the UUID
into the file when it's generated? That's how things normally work in
similar setups such as grub.conf...

> Since the uuids are only looked for after we've already found extlinux.conf
> there's little cost/risk to making them available.
> I realise that assuming extlinux.conf is on the root partition isn't perfect
> but for the common case where it will be, there are many advantages to 
> this.

... and completely avoids the issue of U-Boot making assumptions about
the partition layout that the distro installer used.