| Message ID | CAOMZO5CbJfpVwqHM1RSYdEQH4n1EL67Kt2_tC9TNPxZGMsPevQ@mail.gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Dear Fabio Estevam, > On Fri, Feb 8, 2013 at 2:48 PM, Will Deacon <will.deacon@arm.com> wrote: > > From dc381a5dff9663901a61fe0dd86c986add382281 Mon Sep 17 00:00:00 2001 > > From: Will Deacon <will.deacon@arm.com> > > 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 <festevam@gmail.com> > > Signed-off-by: Will Deacon <will.deacon@arm.com> > > Thanks, Will. > > This makes the kernel to boot again on my mx28evk, so: > > Tested-by: Fabio Estevam <fabio.estevam@freescale.com> > > There are still other issues, which seem to be unrelated to this fix > though: > > I can see the Linux logo and LED activity on my board, but no serial > console. > > Applying Shawn's patch: > > diff --git a/arch/arm/boot/compressed/debug.S > b/arch/arm/boot/compressed/debug.S > index bdb0e25..6e8382d 100644 > --- a/arch/arm/boot/compressed/debug.S > +++ b/arch/arm/boot/compressed/debug.S > @@ -1,4 +1,5 @@ > #include <linux/linkage.h> > +#include <asm/assembler.h> > > #include CONFIG_DEBUG_LL_INCLUDE > > and turning on earlyprintk I see kernel booting and it stops at: > > [ 5.311281] TCP: cubic registered > [ 5.315000] NET: Registered protocol family 17 > [ 5.320843] Key type dns_resolver registered > [ 5.325750] turn off boot console earlycon0 Is the amba-pl011 driver maybe broken ? So far, Wills' and Shawns' patches got me further too, thanks! Best regards, Marek Vasut
On Sun, Feb 10, 2013 at 1:28 AM, Marek Vasut <marex@denx.de> wrote:
> Is the amba-pl011 driver maybe broken ?
At least on mx28evk, ttyAMA0 is not getting registered when running linux-next.
I haven't had a chance to debug it though.
On Sun, Feb 10, 2013 at 1:28 AM, Marek Vasut <marex@denx.de> wrote:
> Is the amba-pl011 driver maybe broken ?
Running Linus' git I get:
[ 0.189156] Serial: AMBA PL011 UART driver
[ 0.191187] 80074000.serial: ttyAMA0 at MMIO 0x80074000 (irq = 221)
is a PL011 rev2
[ 0.487625] console [ttyAMA0] enabled
,but when I run linux-next only the first line shows up.
Hi Will, On Fri, Feb 8, 2013 at 3:14 PM, Fabio Estevam <festevam@gmail.com> wrote: > On Fri, Feb 8, 2013 at 2:48 PM, Will Deacon <will.deacon@arm.com> wrote: > >> From dc381a5dff9663901a61fe0dd86c986add382281 Mon Sep 17 00:00:00 2001 >> From: Will Deacon <will.deacon@arm.com> >> 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 <festevam@gmail.com> >> Signed-off-by: Will Deacon <will.deacon@arm.com> > > Thanks, Will. > > This makes the kernel to boot again on my mx28evk, so: > > Tested-by: Fabio Estevam <fabio.estevam@freescale.com> Do you plan to submit this patch to Russell's patch system? Thanks, Fabio Estevam
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 <festevam@gmail.com> wrote: > > On Fri, Feb 8, 2013 at 2:48 PM, Will Deacon <will.deacon@arm.com> wrote: > > > >> From dc381a5dff9663901a61fe0dd86c986add382281 Mon Sep 17 00:00:00 2001 > >> From: Will Deacon <will.deacon@arm.com> > >> 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 <festevam@gmail.com> > >> Signed-off-by: Will Deacon <will.deacon@arm.com> > > > > Thanks, Will. > > > > This makes the kernel to boot again on my mx28evk, so: > > > > Tested-by: Fabio Estevam <fabio.estevam@freescale.com> > > 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.)
On Sun, Feb 10, 2013 at 02:26:11PM -0200, Fabio Estevam wrote: > On Sun, Feb 10, 2013 at 1:28 AM, Marek Vasut <marex@denx.de> wrote: > > > Is the amba-pl011 driver maybe broken ? > > At least on mx28evk, ttyAMA0 is not getting registered when running linux-next. > > I haven't had a chance to debug it though. Try reverting commit aac73f3 (of: use platform_device_add) and see if it helps. Shawn
On Sat, Feb 16, 2013 at 05:56:13PM +0000, Russell King - ARM Linux wrote: > On Sat, Feb 16, 2013 at 03:41:53PM -0200, Fabio Estevam wrote: > > Hi Will, Hello, > > On Fri, Feb 8, 2013 at 3:14 PM, Fabio Estevam <festevam@gmail.com> wrote: > > 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". I think the branches are actually ok, because the code in question (that is, the kernel code dispatching to and performing the flush) is mapped identically before and after the page table switch. > 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. This is the killer argument. We don't need the maintenance except in a few, tiny places. I've written some patches for that and I'll post them to the list in due course, aiming for 3.10. > 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... Yup. I've also been looking at TLB invalidation as a whole and some optimisations we can do on ARMv7 where we don't *actually* need to use the inner-shareable variants. Non-shareable often suffices and is a win in terms of both performance and power (it makes the deferred flushing on ASID rollover usable by v7 too). Again, I've been hacking in this area so I'll post patches for review once I've got a coherent story. > 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.) Thanks Russell. Will
diff --git a/arch/arm/boot/compressed/debug.S b/arch/arm/boot/compressed/debug.S index bdb0e25..6e8382d 100644 --- a/arch/arm/boot/compressed/debug.S +++ b/arch/arm/boot/compressed/debug.S @@ -1,4 +1,5 @@ #include <linux/linkage.h> +#include <asm/assembler.h> #include CONFIG_DEBUG_LL_INCLUDE