[PATCH 9/9] ARM: vexpress: Config option for early printk console
Pawel Moll
pawel.moll at arm.com
Wed Jul 11 10:23:47 EDT 2012
On Wed, 2012-07-11 at 15:16 +0100, Pawel Moll wrote:
> 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...
... and use DEBUG_LL_VIRT_BASE as the \rv for now, before the change in
head.S happen. Physical 0 on VE is always flash, so it's not a problem.
Pawel
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