On Tue, 12 Feb 2008 08:27:14 -0500 Jerry Van Baren gerald.vanbaren@ge.com wrote:
Bryan O'Donoghue wrote:
Hi Bryan,
I don't think CONFIG_OF_CHOSEN_UPDATE is needed. If it *is* needed, I don't think it *should be* needed and we need to discuss scenarios.
Hey Jerry.
I'd have to say I fundamentally agree with the principal you're putting forward here - i.e. that using a compile time define is a bit inflexible and doubly wrong in that it's manipulating a parameter which ideally shouldn't exist anyway.
The behavior I'm looking for is simply where /chosen/bootargs - doesn't exist in a dts - that U-boot will fill in it's environment bootargs entry in the tree - i.e. it creates /chosen/<prop> if <prop> doesn't exist.
Initially, we did not touch the /chosen node *at all* if it already existed. That was where the "force" flag came from - the criteria wasn't fine grained enough. That behavior was changed in the 1.3.1 time frame to be fine grained: if /chosen exists, but /chosen/<prop> doesn't, that property is created and set to the required value.
That creation won't happen though due to the code fragment below.
If /chosen/<prop> exists, it is overwritten only if the "force" flag is set. What you have added with CONFIG_OF_CHOSEN_UPDATE it a compile time "force" flag setting.
Maybe that is desirable, but I'm going to challenge you to justify it. :-)
Nope it's admitedly a blunt instrument to accomplish stuffing /chosen/<prop> if <prop> doesn't exist.
What the define works around is this in fdt_support.c
/* * If we have a "chosen" node already the "force the writing" * is not set, our job is done. */ if ((nodeoffset >= 0) && !force) return 0;
The default sans CONFIG_OF_CHOSEN_UPDATE in do_bootm_linux is to pass force = 0 - which means if /chosen is present in the dts - then no manipulation of the /chosen entry will be performed - as I read it anyway.
I was thinking that some sort of define would be the least invasive way of changing that.... with a view to the least amount of change being the most likely to be acceptable to other developers - not necessarily the best way to do the thing....