linux-kernel - Re: [PATCH v2] pseries: don't override CONFIG_PPC_PSERIES

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Date:	Fri, 15 Oct 2010 15:01:44 +1100
From:	Michael Ellerman <michael@...erman.id.au>
To:	linasvepstas@...il.com
Cc:	Nishanth Aravamudan <nacc@...ibm.com>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Paul Mackerras <paulus@...ba.org>,
	Brian King <brking@...ux.vnet.ibm.com>,
	Anton Blanchard <anton@...ba.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Frans Pop <elendil@...net.nl>, linuxppc-dev@...ts.ozlabs.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] pseries: don't override CONFIG_PPC_PSERIES_DEBUG

On Thu, 2010-10-14 at 20:54 -0500, Linas Vepstas wrote:
> On 14 October 2010 19:48, Nishanth Aravamudan <nacc@...ibm.com> wrote:
> > eeh and pci_dlpar #undef DEBUG, but I think they were added before the
> > ability to control this from Kconfig. It's really annoying to only get
> > some of the debug messages from these files. Leave the lpar.c #undef
> > alone as it produces so much output as to make the kernel unusable.
> > Update the Kconfig text to indicate this particular quirk :)
> >
> > Signed-off-by: Nishanth Aravamudan <nacc@...ibm.com>
> 
> OK, ignore my last email.
> 
> Acked by: Linas Vepstas <linasvepstas@...il.com>

I guess I'll ack it too seeing I added PPC_PSERIES_DEBUG:

Acked-by: Michael Ellerman <michael@...erman.id.au>

> > --- a/arch/powerpc/platforms/pseries/Kconfig
> > +++ b/arch/powerpc/platforms/pseries/Kconfig
> > @@ -47,6 +47,12 @@ config LPARCFG
> >  config PPC_PSERIES_DEBUG
> >        depends on PPC_PSERIES && PPC_EARLY_DEBUG
> >        bool "Enable extra debug logging in platforms/pseries"
> > +        help
> > +         Say Y here if you want the pseries core to produce a bunch of
> > +         debug messages to the system log. Select this if you are having a
> > +         problem with the pseries core and want to see more of what is
> > +         going on. This does not enable debugging in lpar.c, which must
> > +         be manually done due to its verbosity.
> >        default y
> 
> Umm, I see "default y" and you are not changing this but ... default y
> ?? Really?

Yes, default y if early debug is enabled. Unlike DEBUG_KERNEL,
PPC_EARLY_DEBUG is a pretty good indication that you are doing some
kernel development - because you have to choose exactly which platform
you're working on.

> Also, I am guessing that the lpar spam is due only to a handful of printk's,
> while most of the rest will be infrequent.  Just knock out the
> high-frequency ones...

No they're all related to the HPTE code, so you basically don't want any
of them enabled unless you're debugging that, and most people aren't.

cheers


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