[PATCH 4/4] ARM: uncompress: support uncompress debug for multiplatform build

[Shawn Guo]

On Fri, Jan 11, 2013 at 11:11:16AM -0800, Olof Johansson wrote:
> Hi,
> 
> On Wed, Dec 12, 2012 at 09:45:45PM +0800, Shawn Guo wrote:
> > When moving to multiplatform build, platforms lose the output from
> > decompressor.  Not only does it mean that we will never see message
> > "Uncompressing Linux... done, booting the kernel.", but also that
> > the debug facility in arch/arm/boot/compressed/head.S outputs nothing
> > even DEBUG is turned on.
> > 
> > The patch follows the approach handling DEBUG_LL to create a Kconfig
> > symbol CONFIG_UNCOMPRESS_INCLUDE for choosing the correct uncompress
> > header.  For traditional build, mach/uncompress.h will be included in
> > arch/arm/boot/compressed/misc.c.  For multiplatform build with none
> > DEBUG_LL port enabled, debug/uncompress/dummy.h will be used.  And
> > for multiplatform build with a DEBUG_LL port, platform specific
> > uncompress header like debug/uncompress/imx.h will come to play.
> > 
> > Different from traditional build that uncompress output and DEBUG_LL
> > are two separated pieces, for multiplatform build uncompress output
> > becomes a subset of DEBUG_LL and will not work unless DEBUG_LL is
> > enabled.
> > 
> > The arch/arm/include/debug/uncompress/imx.h is cleaned up and added
> > here as an example to show how this approach works.
> 
> Since this requires you to define a debug uart to get uncompress output,
> it would make more sense to do a generic wrapper that uses the debug
> code generically, instead of having to add this kind of wrapper for
> every platform. That would solve it for all of them at once.
> 
I'm not entirely sure about what you mean here.  Can you please
elaborate that generic wrapper in your mind a little bit?

Shawn