[PATCH 9/9] ARM: vexpress: Config option for early printk console

[Pawel Moll]

On Wed, 2012-07-11 at 15:09 +0100, Will Deacon wrote:
> > +#else /* CONFIG_DEBUG_LL_UART_NONE */
> > +
> > +		.macro	addruart, rp, rv, tmp
> > +		/*
> > +		 * Have to provide reasonable dummy values,
> > +		 * otherwise code in head.S crashes badly...
> > +		 */
> > +		mov	\rp, #0
> > +		mov	\rv, #0
> > +		.endm
> 
> Eek, this means we take out an I/O section mapping at zero, doesn't it?
> Is that really a good idea? It scares me because (a) it's below PAGE_OFFSET
> and (b) we don't know consistently what's at physical address 0.
> 
> Perhaps we could change head.S to avoid the mapping if addruart returns a
> NULL virtual address?

Sure (care to prepare a patch? ;-), but this will have to go through
Russell not arm-soc, so it won't be a part of this update. And I'll
remove the comment...

Cheers!

Paweł