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SubjectRe: [PATCH 1/4] Add a basic debugging framework for memory initialisation
On (21/04/08 17:14), Ingo Molnar didst pronounce:
>
> * Mel Gorman <mel@csn.ul.ie> wrote:
>
> > +config DEBUG_MEMORY_INIT
> > + bool "Debug memory initialisation"
> > + depends on DEBUG_KERNEL
> > + help
> > + Enable this to turn on debug checks during memory initialisation. By
> > + default, sanity checks will be made on the memory model and
> > + information provided by the architecture. What level of checking
> > + made and verbosity during boot can be set with the
> > + mminit_debug_level= command-line option.
> > +
> > + If unsure, say N
>
> should be "default y" - and perhaps only disable-able on
> CONFIG_EMBEDDED.

Ok, that would be something like the following?

bool "Debug memory initialisation" if DEBUG_KERNEL && EMBEDDED
depends on DEBUG_KERNEL
default !EMBEDDED

This will slow up boot slightly on debug kernels as the additional checks
are made. It'll remain to be seen as to whether this is a problem for people
or not. I doubt it'll be noticed.

> We generally want such bugs to pop up as soon as
> possible, and the sanity checks should only go away if someone
> specifically aims for lowest system footprint.
>

Seems fair and it's the second time this has been suggested (off-list reviewer
again). The only potential gotcha is if a sanity check is introduced that is
itself broken. It should be very obvious when this type of bug occurs though.

> the default loglevel for debug printouts might deserve another debug
> option - but the core checks should always be included, and _errors_
> should always be printed out.
>

I'll replace mminit_debug_level with mminit_loglevel that determines whether
information is printed at KERN_DEBUG or not. This matches what other similar
debug-frameworks are doing. I'll make sure errors always get printed.

Thanks

--
Mel Gorman
Part-time Phd Student Linux Technology Center
University of Limerick IBM Dublin Software Lab


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