[Power.org:parch] devicetree: Musings on reserved regions

[Jimi Xenidis]

On Feb 7, 2011, at 3:45 PM, Grant Likely wrote:
> 
> On Mon, Feb 7, 2011 at 2:39 PM, Benjamin Herrenschmidt
> <benh at kernel.crashing.org> wrote:
>> 
>>> In addition to the reserved regions block in the header, define a set
>>> of properties in the memory node that specify the reserved regions
>>> with the name reflecting the usage.
>>> For example:
>>> 
>>>       memory at 0 {
>>>               device_type = "memory";
>>>               reg = <0 0x40000000>;
>>>               reserved-ramdisk = <0xc00000 0x200000>; /* 2MB ramdisk */
>>>               reserved-dtb = <0xbf0000 0x1000>; /* devicetree */
>>>               reserved-fb0 = 0x1000000 0x400000>; /* framebuffer */
>>>       };
>>> 
>>> Each reserved property would start with "reserved-" followed by a
>>> name.  reserved-ramdisk and reserved-dtb would be reserved for ramdisk
>>> and dtb images respectively.  Other names could also be defined; for
>>> example, reserved-openfirmware.
>> 
>> I very much dislike the list of properties with magic names. I'd rather
>> have a pair of properties containing lists (reserved-names and
>> reserved-ranges).
> 
> Heh, I have very much the opposite opinion.  I'd rather have property
> names that match the usage than have the names and values split into
> two properties.  To me, keeping them together is more tasteful.  Queue
> the debate...  :-)

ok.. here goes nothing...
When I see these "reservations", it makes me think that they should be nodes anyway. (off root?)
Once we have nodes for these interesting things, perhaps the next step is to just have a "reserved" property for these nodes?
so:
	ramdisk@<addr> {
		reg = < addr, size >;
		format = < "gzip", "cpio" >;  // optional, order of wrapper?
		reserved;
	}

No, I'm not ready to propose the ramdisk node, but it is something to consider.

-JX


> 
> g.
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