From mboxrd@z Thu Jan 1 00:00:00 1970 From: Giuseppe CAVALLARO Date: Fri, 05 Sep 2008 11:35:25 +0000 Subject: Re: [PATCH] fix build failure when compiling without TRACE_IRQFLAGS_SUPPORT Message-Id: <48C1197D.8000608@st.com> List-Id: References: <48C0D2A4.90208@st.com> In-Reply-To: <48C0D2A4.90208@st.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-sh@vger.kernel.org Paul Mundt wrote: > On Fri, Sep 05, 2008 at 08:33:08AM +0200, Giuseppe CAVALLARO wrote: > >> Hi All, >> playing with the kernel configuration we noticed that the >> kernel doesn't build if TRACE_IRQFLAGS_SUPPORT is >> forced off. So this patch just fixes it. >> >> Anyway, we are wondering why it's not possible to disable >> this option from Kconfig. >> Reading the Documentation/irqflags-tracing.txt, this option is >> "needed for CONFIG_PROVE_SPIN_LOCKING and >> CONFIG_PROVE_RW_LOCKING to be offered by the generic >> lock debugging code." >> But we cannot find any references to PROVE_RW_LOCKING etc. >> May be removed? >> >> > Have you noticed this problem on non-sh platforms also? If so, you should > resend this patch to linux-kernel with the linux-sh list CCed. > we'll send the patch soon. > The config dependencies are a bit of a mess, but it's all quite > functional. CONFIG_PROVE_RW_LOCKING is bogus though, it's actually > CONFIG_PROVE_LOCKING. Anyways, take a look at lib/Kconfig.debug and it > should all be pretty obvious. > > TRACE_IRQFLAGS_SUPPORT is used by quite a lot of things, lockdep, lock > stat, preempt debug, etc. You really do _not_ want to disable this > option, especially as it is a _support_ option, not a functional one. > > CONFIG_TRACE_IRQFLAGS itself is what introduces extra overhead, and while > this depends on TRACE_IRQFLAGS_SUPPORT, it also has a dependency on > DEBUG_KERNEL. Thus, you will never see any of this stuff with kernel > debugging disabled. Most of this stuff is hidden away from the user in > Kconfig for a good reason :-) Sure, all sounds clear now. Thanks!