Re: [Xen-devel] [PATCH 0/16] arm: support for initial modules (e.g. dom0) and DTB supplied in RAM

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Thu, 2012-09-06 at 15:46 +0100, David Vrabel wrote:
> On 03/09/12 14:28, Ian Campbell wrote:
> > The following series implements support for initial images and DTB in
> > RAM, as opposed to in flash (dom0 kernel) or compiled into the
> > hypervisor (DTB). It arranges to not clobber these with either the h/v
> > text on relocation or with the heaps and frees them as appropriate.
> > 
> > Most of this is independent of the specific bootloader protocol which is
> > used to tell Xen where these modules actually are, but I have included a
> > simple PoC bootloader protocol based around device tree which is similar
> > to the protocol used by Linux to find its initrd
> > (where /chosen/linux,initrd-{start,end} indicate the physical address).
> > 
> > In the PoC the modules are listed in the chosen node starting
> > with /chosen/nr-modules which contains the count and then /chosen/module
> > %d-{start,end} which gives the physical address of the module
> > and /chosen/module%d-args which give its command line.
> 
> Until there is an agreement on this protocol I would prepend a "xen,"
> prefix to the node names (xen,nr-modules etc.).

OK.

> bootargs instead of args would be more consistent perhaps. So,
> module1-args becomes xen,module1-bootargs.
> 
> The proposed protocol is functional and useful using nodes for each
> module seems to be more device-tree-ish. I think in the longer term,
> perhaps something like the following would be better?

I rather suspect I'm going to end up porting multiboot to ARM. But you
are right that this looks like a better DTish way than mine.

> 
> chosen {
>     module@1 {

Are these normally 1 based or 0 based in DT?

>         compatible = "multiboot-module";
>         regs = <0x12345678 0x01000>;

Is this start and length? This relates somehow to #address-cells or
something doesn't it?

>         bootargs = "frob";
>     };
>     module@2 {
>         compatible = "multiboot-module";
>         regs = <0x12345678 0x01000>;
>     }
> }
> 
> David



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