USB support on mpc5200 broken
Peter Korsgaard
jacmet at sunsite.dk
Tue Sep 30 03:05:34 EST 2008
>>>>> "Sven" == Sven Luther <sven at genesi-usa.com> writes:
Hi,
>> This, of course, is exactly why I *don't* recommend embedded platforms
>> move to including the device tree in the flashed firmware. Keeping
>> the device tree in the bootwrapper means that it *is* updated with the
>> kernel and we don't have to mess around with as much backwards
>> compatibility junk.
Sven> This completely defeats the purpopse of having a separate
Sven> device tree though, no ? I mean, we could just as well hardcode
Sven> the device-tree info in the kernel in this case ?
Well, yes and no. The device tree brings a number of advantages (and a
few disadvantages as well), one of those being the potential
decoupling of kernel and DT. Even if you don't make use of that
feature in a production build you still have the other advantages
(E.G. easy compile test of multiple boards, limited
repeated-these-are-my-platform-devices code in board files, ...).
Sven> (In embedded cases, the kernel is usyually in the flash as
Sven> well, so you just upgrade both at the same time :)
Sure, but if you do that you might as well include them in a single
uImage because:
- They are always in sync
- You don't waste flash space (E.G. the DT is very small, but you
waste a complete flash sector)
With uImage.<platform> U-Boot can still fix up the tree before booting
the kernel, so you don't lose any functionality (E.G. if you
enable/disable certain nodes based on what option boards are
available).
--
Bye, Peter Korsgaard
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