[U-Boot] [PATCH 1/2] ARM: bootm: allow skipping fdt memory node fixup

Wolfgang Denk wd at denx.de
Wed Feb 20 15:11:19 CET 2013


Dear Rob,

In message <20130219231428.44C8A200536 at gemini.denx.de> I wrote:
> 
> > There is no such way defined to flag that and I'm not going to invent
> > one. It's not that the memory node is immutable, but the default should
> > not be "needs fixups". No one puts purposely wrong data in their DT. So
> > therefore all data should be immutable? What happens when we need to
> > fixup immutable data?
> 
> There is for example the "status" property, which can take the values
> "okay" or "disabled".  This is used in other places for not so
> unsimilar purposes.

Actually it's even much simpler than that.

If you look for example at PPC, you will see many memory nodes in the
DTB that look like this one (this example is from
arch/powerpc/boot/dts/canyonlands.dts):

	memory {
		device_type = "memory";
		reg = <0x00000000 0x00000000 0x00000000>; /* Filled in by U-Boot */
	};

I. e. the DT provides only dummy values.

How about checking for these - if the DT contains such dummy entries,
U-Boot will insert valid data; if the DT already contains real data,
these take preference?  [And if the latter differ from what U-Boot
thinks is correct, then a big fat warning should be issued!]

Best regards,

Wolfgang Denk

-- 
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