From mboxrd@z Thu Jan 1 00:00:00 1970 From: linux@arm.linux.org.uk (Russell King - ARM Linux) Date: Sat, 16 Feb 2013 17:56:13 +0000 Subject: mx28evk does not boot with linux-next 20130207 In-Reply-To: References: <20130207125801.GA19091@S2101-09.ap.freescale.net> <20130208161811.GW17833@n2100.arm.linux.org.uk> <20130208164858.GA32318@mudshark.cambridge.arm.com> Message-ID: <20130216175613.GP17833@n2100.arm.linux.org.uk> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Sat, Feb 16, 2013 at 03:41:53PM -0200, Fabio Estevam wrote: > Hi Will, > > On Fri, Feb 8, 2013 at 3:14 PM, Fabio Estevam wrote: > > On Fri, Feb 8, 2013 at 2:48 PM, Will Deacon wrote: > > > >> From dc381a5dff9663901a61fe0dd86c986add382281 Mon Sep 17 00:00:00 2001 > >> From: Will Deacon > >> Date: Fri, 8 Feb 2013 16:41:19 +0000 > >> Subject: [PATCH] ARM: tlb: fix branch predictor maintenance for ARMv6 > >> > >> The BPIALL operation is not available on all CPUs, so ensure that we > >> only execute it on processors implementing the instruction. > >> > >> Reported-by: Fabio Estevam > >> Signed-off-by: Will Deacon > > > > Thanks, Will. > > > > This makes the kernel to boot again on my mx28evk, so: > > > > Tested-by: Fabio Estevam > > Do you plan to submit this patch to Russell's patch system? No, I've suggested to Will that we deal with the branch predictor a different way, because we actually rarely need to flush it. Plus, these patches are architecturally wrong (you're not allowed to branch between the BP maintanence instruction and the following isb/dsb instructions because the branches become "unpredictable". Plus, we _used_ to flush the BP here, and I did an amount of work to remove the flushing because it just wasn't necessary - all the paths at that time just didn't require it. What we have ended up with today is a couple of paths which do, both of which are arch-specific code, and we should deal with that in an arch specific way. Will has been working on a patch to do that... In the mean time, I'm dropping 5d9e3f9d7fcd7d09feb5d23974768a60bcea4094 which added the BP maintanence (I actually said to Will that I'd already done this but it appears not.)