From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752009AbcI0E4K (ORCPT ); Tue, 27 Sep 2016 00:56:10 -0400 Received: from asavdk3.altibox.net ([109.247.116.14]:58921 "EHLO asavdk3.altibox.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750877AbcI0E4J (ORCPT ); Tue, 27 Sep 2016 00:56:09 -0400 X-Greylist: delayed 574 seconds by postgrey-1.27 at vger.kernel.org; Tue, 27 Sep 2016 00:56:08 EDT Date: Tue, 27 Sep 2016 06:46:25 +0200 From: Sam Ravnborg To: Babu Moger Cc: peterz@infradead.org, mingo@redhat.com, akpm@linux-foundation.org, keescook@chromium.org, dan.j.williams@intel.com, aryabinin@virtuozzo.com, tj@kernel.org, linux-kernel@vger.kernel.org, sparclinux@vger.kernel.org Subject: Re: [PATCH v2 1/2] config: Add new CONFIG_PROVE_LOCKING_SMALL Message-ID: <20160927044625.GA13264@ravnborg.org> References: <1474929098-68914-1-git-send-email-babu.moger@oracle.com> <1474929098-68914-2-git-send-email-babu.moger@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1474929098-68914-2-git-send-email-babu.moger@oracle.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-CMAE-Score: 0 X-CMAE-Analysis: v=2.2 cv=WJY9ZTkR c=1 sm=1 tr=0 a=Ij76tQDYWdb01v2+RnYW5w==:117 a=Ij76tQDYWdb01v2+RnYW5w==:17 a=kj9zAlcOel0A:10 a=yPCof4ZbAAAA:8 a=dqWOSVUKs1aXyGlsAdwA:9 a=CjuIK1q_8ugA:10 a=2lfDSYhZ3Z6b8uxcDO-Z:22 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Babu. On Mon, Sep 26, 2016 at 03:31:37PM -0700, Babu Moger wrote: > Adding the new config parameter CONFIG_PROVE_LOCKING_SMALL for sparc. > > This feature limits the space used for "Lock debugging: prove locking > correctness" by about 4MB. The current sparc systms have the limitation of > 32MB size for kernel size including .text, .data and .bss sections. With > PROVE_LOCKING feature, the kernel size could grow beyond this limit and > causing system bootup issues. With this option, kernel limits the size > of the entries of lock_chains, stack_trace etc. so that kernel fits in > required size limit. This is only visible for sparc. > > Signed-off-by: Babu Moger > --- > lib/Kconfig.debug | 17 +++++++++++++++++ > 1 files changed, 17 insertions(+), 0 deletions(-) > > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug > index b9cfdbf..c79de25 100644 > --- a/lib/Kconfig.debug > +++ b/lib/Kconfig.debug > @@ -1035,6 +1035,7 @@ config PROVE_LOCKING > select DEBUG_MUTEXES > select DEBUG_LOCK_ALLOC > select TRACE_IRQFLAGS > + select PROVE_LOCKING_SMALL if SPARC > default n > help > This feature enables the kernel to prove that all locking > @@ -1070,6 +1071,22 @@ config PROVE_LOCKING > > For more details, see Documentation/locking/lockdep-design.txt. > > +config PROVE_LOCKING_SMALL > + bool "Limit the space for prove locking correctness" > + depends on PROVE_LOCKING && SPARC > + help > + This feature limits the space used for "Lock debugging: prove > + locking correctness" by about 4MB. In sparc system, all the > + kernel's code, data, and bss, must have locked translations in > + the TLB so that it does not hit TLB misses. The current sparc > + chips have 8 TLB entries available that may be locked down, and > + with a 4mb page size, this gives a maximum of 32mb of memory for > + the kernel size. With PROVE_LOCKING feature, the kernel size could > + grow beyond this limit and causing system bootup issues. With > + this option, kernel limits the size of the entries of lock_chains, > + stack_trace etc. to debug PROVE_LOCKING so that kernel size fits > + in 32MB. This is only visible for SPARC. Since this is only relevant for sparc, and for sparc this is "select"ed, then there is limited/no gain having this as a visible menu config option. How about adding just a simple non-visible config symbol: config PROVE_LOCKING_SMALL bool The nice help text can be added to the H file, and the select can be move to the sparc/Kconfig file where it really belongs. Sam