Re: [PATCH] msm: fix debug-macro.S build failure

[Russell King - ARM Linux <linux@arm.linux.org.uk>]

On Thu, Oct 28, 2010 at 09:41:06AM -0700, Daniel Walker wrote:
> On Thu, 2010-10-28 at 17:35 +0100, Russell King - ARM Linux wrote:
> > On Thu, Oct 28, 2010 at 09:30:13AM -0700, Daniel Walker wrote:
> > > On Wed, 2010-10-27 at 22:30 -0400, Nicolas Pitre wrote:
> > > > On Wed, 27 Oct 2010, Russell King - ARM Linux wrote:
> > > > 
> > > > > > +#else
> > > > > > +	.macro	addruart, rx, tmp
> > > > > 
> > > > > addruart is now expected to return two values, and 'tmp' ends up being
> > > > > misleading.  This is a recipe for mistakes unless this is corrected.
> > > > > It should be 'rp, rv' instead of 'rx, tmp'.
> > > > 
> > > > Also, it is probably not a good idea to return nothing. Otherwise the 
> > > > code using those macros will then work on random values that just 
> > > > happened to be in the corresponding register at the call location.
> > > 
> > > Should we have something in generic arm code that allows this to just be
> > > turned off? Ideally we don't want any of this stuff even running.
> > 
> > If you don't want it, don't enable DEBUG_LL.  DEBUG_LL is what you
> > enable for initial board bring-up and once you're getting kernel
> > messages via standard console drivers, you disable it.
> 
> This board doesn't have the ability to support DEBUG_LL .. I don't want
> the user to have the option to even select that.

There is no such option present - and there never has been.  This raises
the question about what you did before with .phys_io and .io_pg_offst
on these platforms which can't support it at all.

Effectively, rp is what you would've returned as .phys_io, and rv is
the virtual address corresponding to .io_pg_offst - so just replicate
that behaviour.  But do not leave this function empty otherwise if you
enable DEBUG_LL, you'll get unpredictable behaviour.

All that you'll then have is a temporary mapping which is torn-down
when the kernel initializes the page tables properly.