Making ARM multiplatform kernels DT-only?

[arnd@arndb.de (Arnd Bergmann)]

Hi everyone,

I've been discussing multiplatform kernels with a few people recently,
and we will have a lot of discussion sessions about this at Linaro
Connect in Hong Kong.

One question that came up repeatedly is whether we should support all
possible board files for each platform in a multiplatform kernel,
or just the ones that are already using DT probing. I would like
to get a quick poll of opinions on that and I've tried to put those
people on Cc that would be most impacted by this, i.e. the maintainers
for platforms that have both DT and non-DT board files at the moment.

My feeling is that we should just mandate DT booting for multiplatform
kernels, because it significantly reduces the combinatorial space
at compile time, avoids a lot of legacy board files that we cannot
test anyway, reduces the total kernel size and gives an incentive
for people to move forward to DT with their existing boards.

The counterargument is that we won't be able to support all the
boards we currently do when the user switches on multiplatform,
but I think that is acceptable.
Note that I would still want to allow users to build platforms
separately in order to enable the ATAG style board files, even
for platforms that are not multiplatform capable.

Other opinions?

	Arnd