From: Peter Korsgaard <jacmet@sunsite•dk>
To: Sven Luther <sven@genesi-usa•com>
Cc: linuxppc-dev <Linuxppc-dev@ozlabs•org>
Subject: Re: USB support on mpc5200 broken
Date: Mon, 29 Sep 2008 19:05:34 +0200 [thread overview]
Message-ID: <87iqseopb5.fsf@macbook.be.48ers.dk> (raw)
In-Reply-To: <20080929151854.GA29375@powerlinux.fr> (Sven Luther's message of "Mon\, 29 Sep 2008 17\:18\:54 +0200")
>>>>> "Sven" == Sven Luther <sven@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
next prev parent reply other threads:[~2008-09-29 17:05 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-09-24 21:51 USB support on mpc5200 broken Jon Smirl
2008-09-25 1:09 ` Jon Smirl
2008-09-25 1:50 ` Benjamin Herrenschmidt
2008-09-25 2:40 ` Jon Smirl
2008-09-29 1:30 ` Matt Sealey
2008-09-29 3:43 ` David Gibson
2008-09-29 14:14 ` Jon Smirl
2008-09-29 14:22 ` Peter Korsgaard
2008-09-29 14:28 ` Jon Smirl
2008-09-29 15:07 ` Peter Korsgaard
2008-09-29 20:18 ` Scott Wood
2008-09-29 21:04 ` Jon Smirl
2008-09-29 22:02 ` Grant Likely
2008-09-30 15:20 ` Matt Sealey
2008-10-01 3:31 ` Benjamin Herrenschmidt
2008-10-01 9:46 ` Carsten Schlote
2008-10-01 10:36 ` Benjamin Herrenschmidt
2008-10-06 21:06 ` Matt Sealey
2008-09-29 15:18 ` Sven Luther
2008-09-29 17:05 ` Peter Korsgaard [this message]
2008-09-30 1:12 ` David Gibson
2008-09-30 1:24 ` Raquel and Bill
2008-09-30 15:15 ` Matt Sealey
2008-11-03 15:41 ` Grant Likely
2008-11-03 16:21 ` Jon Smirl
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