From mboxrd@z Thu Jan 1 00:00:00 1970 From: dave.martin@linaro.org (Dave Martin) Date: Fri, 20 Jan 2012 15:02:51 +0000 Subject: Building of arch/arm/plat-mxc/ssi-fiq.S failed w/ THUMB2 enabled? In-Reply-To: <20120120115606.GL1068@n2100.arm.linux.org.uk> References: <20111202102418.GT26618@pengutronix.de> <20111202133911.GC2892@localhost.localdomain> <20120120115606.GL1068@n2100.arm.linux.org.uk> Message-ID: <20120120150251.GC2046@linaro.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Fri, Jan 20, 2012 at 11:56:06AM +0000, Russell King - ARM Linux wrote: > On Fri, Dec 02, 2011 at 01:39:11PM +0000, Dave Martin wrote: > > Is this code still used on ARMv7 and above? FIQ is not normally > > available for Linux interrupts on hardware which makes use of the > > TrustZone security extensions. Plus, on modern hardware with a deep > > memory hierarchy, FIQ is may not be all that "fast" either, due to > > cache/TLB effects. > > It's worth pointing out that people end up using FIQs for certain things > because the hardware requires you to do it. So if a platform is using > them, they're probably not doing it out of choice, but are doing it > because it's a baseline requirement to get something working. Agreed -- but I'm wondering whether this code is actually non-relevant to newer platforms, and is only being built at all because of a non-relevant driver being included in mx5_defconfig, or due to some Kconfig anomaly. If this is really non-relevant to any >= v7 platform, we just need for fix Kconfig : this code should never ever be built into a Thumb-2 kernel in that case. Unfotunately I don't have the i.MX hardware knowledge to answer that "if" though... it's just a hunch on my part. One of the i.MX guys will have to comment on that. Cheers ---Dave