Re: [08/36] AArch64: Kernel booting and initialisation

From: Catalin Marinas
Date: Tue Jul 24 2012 - 12:24:32 EST


On Mon, Jul 23, 2012 at 09:52:22PM +0100, Christopher Covington wrote:
> Hi Catalin and Stephen,
>
> Catalin Marinas - July 8, 2012, 9:18 a.m.
> > On Fri, Jul 06, 2012 at 10:32:54PM +0100, Stephen Warren wrote:
> >
> >> Also, on Tegra at least and perhaps OMAP too, there are a few parts
> >> of earlyprintk serial port setup (i.e. port selection) which happen
> >> as part of the decompressor rather than the main kernel image, so
> >> we'd have to re-jig that too.
> >
> > Whatever we did on AArch32, if it was useful and we want to follow a
> > similar model it needs porting given that the code cannot be shared. So
> > there is nothing to re-jig but rather implement.
> >
> > As for earlyprintk, you can initialise it in the decompressed kernel
> > anyway. But even though it's a useful debugging tool, it goes against
> > the single Image aim (at least the current printascii/addruart
> > implementation). I don't have a proper implementation yet.
>
> Would DCC [1] be a reasonably commonly available early printk mechanism
> for the single image to provide?

Yes, this can be implemented but I think it has its own restrictions,
requiring a JTAG connection.

--
Catalin
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