Re: [PATCH] arm: choose debug/uncompress.h include when uncompressdebug is disabled

From: Russell King - ARM Linux
Date: Wed Jul 17 2013 - 11:12:38 EST


On Wed, Jul 17, 2013 at 02:25:38PM +0100, Stefano Stabellini wrote:
> On Mon, 15 Jul 2013, Julien Grall wrote:
> > Even if uncompress debug is disabled, some board will continue to print
> > information during uncompress step.
>
> Are you talking about DEBUG_UNCOMPRESS?
> Should I read the sentence as "even if DEBUG_UNCOMPRESS is not selected,
> some board will continue to print information during the uncompress step"?
>
> Isn't this a bug in the platform specific code that should be fixed anyway?

Hang on, let's be clear what's going on here.

1. The normal output from the decompressor is *not* debugging. By that
I mean the "Uncompressing kernel... done" message. That is part of
user output.

2. In non-multiplatform environments, the decompressor will normally use
the putc/flush functions found in arch/arm/mach-*/include/mach/uncompress.h
to implement its output, irrespective of the DEBUG_UNCOMPRESS setting.
(An interesting point is that DEBUG_UNCOMPRESS really should depend on
MULTIPLATFORM so that this point is explicit - the option requires
MULTIPLATFORM to be set.)

3. DEBUG_UNCOMPRESS allows the functions which we've implemented for LL
debug to be re-used for decompressor output.

4. When DEBUG_UNCOMPRESS is not set in a multiplatform kernel, the
decompressors putc() and flush() functions are stubbed out.

So, it's quite right that you get output from the decompressor even when
DEBUG_UNCOMPRESS is not set. There's no problem with that.
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