Re: [Xen-devel] [PATCH 04/12] arm: parse modules from DT during early boot.

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

> > diff --git a/docs/misc/arm/device-tree/booting.txt 
> > b/docs/misc/arm/device-tree/booting.txt
> > new file mode 100644
> > index 0000000..2609450
> > --- /dev/null
> > +++ b/docs/misc/arm/device-tree/booting.txt
> > @@ -0,0 +1,27 @@
> > +Xen is passed the dom0 kernel and initrd via a reference in the /chosen
> > +node of the device tree.
> > +
> > +Each node has the form /chosen/module@<N> and contains the following
> > +properties:
> 
> Wouldn't it be better to move all the modules under /chosen/modules or
> /chosen/multiboot?

Why, what's the benefit?

I'm happy to do whatever is more normal in DT. Is that this:
        /foo/bar@1
        /foo/bar@2
or
        /foo/bar/bar@1
        /foo/bar/bar@2

The second (which I think is what you are suggesting) seems pretty
redundant.

> 
> 
> > +- compatible
> > +
> > +   Must be "xen,multiboot-module"
> > +
> > +- start
> > +
> > +   Physical address of the start of this module
> > +
> > +- end
> > +
> > +   Physical address of the end of this module
> 
> start and end could be encoded as one reg

Done.

> 
> 
> > +- bootargs (optional)
> > +
> > +   Command line associated with this module
> > +
> > +The following modules are understood
> > +
> > +- 1 -- the domain 0 kernel
> > +- 2 -- the domain 0 ramdisk
> 
> It would be nice if we could express this via the compatible property
> instead.
> So the linux kernel could be compatible "linux,kernel" and the initrd
> "linux,initrd", in addition to (or instead of) "xen,multiboot-module".
> Given that they go from the most specific to the less specific, it would
> become:
> 
> compatible = "linux,kernel", "xen,multiboot-module";

This bakes the word "linux" into the interface and would require a new
compatible tag and code changes in Xen for each new dom0 kernel type,
which I think we want to avoid. (maybe the code changes are unavoidable
in practice, but in principal...)

"xen,dom0-kernel", "xen,multiboot-module"

Might be an option?

I'm going to repost what I have without changing this bit yet.

Ian.



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