From: Paul Walmsley <paul@pwsan.com>
To: Will Deacon <will.deacon@arm.com>
Cc: Santosh Shilimkar <santosh.shilimkar@ti.com>,
Russell King - ARM Linux <linux@arm.linux.org.uk>,
Rajendra Nayak <rnayak@ti.com>,
"linux-omap@vger.kernel.org" <linux-omap@vger.kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH] ARM: v6: avoid read_cpuid_ext() on ARM1136r0 in cache_ops_need_broadcast()
Date: Sun, 28 Jul 2013 19:47:15 +0000 (UTC) [thread overview]
Message-ID: <alpine.DEB.2.02.1307281945530.23852@utopia.booyaka.com> (raw)
In-Reply-To: <20130728111038.GA9374@mudshark.cambridge.arm.com>
Hi Will
On Sun, 28 Jul 2013, Will Deacon wrote:
> On Sun, Jul 28, 2013 at 06:43:24AM +0100, Paul Walmsley wrote:
> >
> > Commit 621a0147d5c921f4cc33636ccd0602ad5d7cbfbc ("ARM: 7757/1: mm:
> > don't flush icache in switch_mm with hardware broadcasting") breaks
> > the boot on OMAP2430SDP with omap2plus_defconfig. Tracked to an
> > undefined instruction abort from the CP15 read in
> > cache_ops_need_broadcast(). It turns out that early ARM1136 variants
> > don't support several CP15 registers that later ARM cores do.
> > ARM1136JF-S TRM section 3.2.1 "Register allocation" has the details.
>
> Intriguing... I wouldn't expect a cp15 read to be emitted for 1136, since
> the SMP_ON_UP magic should have caused is_smp() to return false.
>
...
> So we should have returned 0 here without exploding (this just reads a
> .globl initialised in head.S). Are we somehow misidentifying your 1136
> as an SMP core?
You're right - the is_arm1136_r0() logic is completely unnecessary - it's
just the 'asm volatile' that makes the difference.
- Paul
WARNING: multiple messages have this Message-ID (diff)
From: paul@pwsan.com (Paul Walmsley)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] ARM: v6: avoid read_cpuid_ext() on ARM1136r0 in cache_ops_need_broadcast()
Date: Sun, 28 Jul 2013 19:47:15 +0000 (UTC) [thread overview]
Message-ID: <alpine.DEB.2.02.1307281945530.23852@utopia.booyaka.com> (raw)
In-Reply-To: <20130728111038.GA9374@mudshark.cambridge.arm.com>
Hi Will
On Sun, 28 Jul 2013, Will Deacon wrote:
> On Sun, Jul 28, 2013 at 06:43:24AM +0100, Paul Walmsley wrote:
> >
> > Commit 621a0147d5c921f4cc33636ccd0602ad5d7cbfbc ("ARM: 7757/1: mm:
> > don't flush icache in switch_mm with hardware broadcasting") breaks
> > the boot on OMAP2430SDP with omap2plus_defconfig. Tracked to an
> > undefined instruction abort from the CP15 read in
> > cache_ops_need_broadcast(). It turns out that early ARM1136 variants
> > don't support several CP15 registers that later ARM cores do.
> > ARM1136JF-S TRM section 3.2.1 "Register allocation" has the details.
>
> Intriguing... I wouldn't expect a cp15 read to be emitted for 1136, since
> the SMP_ON_UP magic should have caused is_smp() to return false.
>
...
> So we should have returned 0 here without exploding (this just reads a
> .globl initialised in head.S). Are we somehow misidentifying your 1136
> as an SMP core?
You're right - the is_arm1136_r0() logic is completely unnecessary - it's
just the 'asm volatile' that makes the difference.
- Paul
next prev parent reply other threads:[~2013-07-28 19:47 UTC|newest]
Thread overview: 80+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-07-22 18:07 OMAP2430 SDP boot broken after Linus' rmk merge Paul Walmsley
2013-07-22 18:07 ` Paul Walmsley
2013-07-22 18:43 ` Russell King - ARM Linux
2013-07-22 18:43 ` Russell King - ARM Linux
2013-07-22 20:07 ` Paul Walmsley
2013-07-22 20:07 ` Paul Walmsley
2013-07-23 7:03 ` Rajendra Nayak
2013-07-23 7:03 ` Rajendra Nayak
2013-07-23 7:07 ` Paul Walmsley
2013-07-23 7:07 ` Paul Walmsley
2013-07-23 9:05 ` Rajendra Nayak
2013-07-23 9:05 ` Rajendra Nayak
2013-07-24 13:56 ` Will Deacon
2013-07-24 13:56 ` Will Deacon
2013-07-24 14:17 ` Santosh Shilimkar
2013-07-24 14:17 ` Santosh Shilimkar
2013-07-24 14:20 ` Will Deacon
2013-07-24 14:20 ` Will Deacon
2013-07-24 14:45 ` Santosh Shilimkar
2013-07-24 14:45 ` Santosh Shilimkar
2013-07-27 4:10 ` Paul Walmsley
2013-07-27 4:10 ` Paul Walmsley
2013-07-27 12:22 ` Will Deacon
2013-07-27 12:22 ` Will Deacon
2013-07-28 5:38 ` Paul Walmsley
2013-07-28 5:38 ` Paul Walmsley
2013-07-28 5:46 ` [PATCH] ARM: v6: avoid remaining accesses to missing CP15 registers on ARM1136 r0 Paul Walmsley
2013-07-28 5:46 ` Paul Walmsley
2013-07-28 5:58 ` Paul Walmsley
2013-07-28 5:58 ` Paul Walmsley
2013-07-28 6:00 ` [PATCH v2] " Paul Walmsley
2013-07-28 6:00 ` Paul Walmsley
2013-07-28 19:58 ` Paul Walmsley
2013-07-28 19:58 ` Paul Walmsley
2013-07-28 5:43 ` [PATCH] ARM: v6: avoid read_cpuid_ext() on ARM1136r0 in cache_ops_need_broadcast() Paul Walmsley
2013-07-28 5:43 ` Paul Walmsley
2013-07-28 11:10 ` Will Deacon
2013-07-28 11:10 ` Will Deacon
2013-07-28 11:52 ` Russell King - ARM Linux
2013-07-28 11:52 ` Russell King - ARM Linux
2013-07-28 19:56 ` Paul Walmsley
2013-07-28 19:56 ` Paul Walmsley
2013-07-28 19:47 ` Paul Walmsley [this message]
2013-07-28 19:47 ` Paul Walmsley
2013-07-28 20:16 ` [PATCH] ARM: v6: prevent gcc from reordering extended CP15 reads above is_smp() test Paul Walmsley
2013-07-28 20:16 ` Paul Walmsley
2013-07-29 7:30 ` Tony Lindgren
2013-07-29 7:30 ` Tony Lindgren
2013-07-29 10:02 ` Will Deacon
2013-07-29 10:02 ` Will Deacon
2013-07-30 10:58 ` Paul Walmsley
2013-07-30 10:58 ` Paul Walmsley
2013-07-30 11:32 ` [PATCH v2] ARM: v6: prevent gcc 4.5 " Paul Walmsley
2013-07-30 11:32 ` Paul Walmsley
2013-07-30 15:04 ` Will Deacon
2013-07-30 15:04 ` Will Deacon
2013-07-24 14:52 ` OMAP2430 SDP boot broken after Linus' rmk merge Russell King - ARM Linux
2013-07-24 14:52 ` Russell King - ARM Linux
2013-07-24 15:40 ` OMAP4430 SDP boot issues.. (Was Re: OMAP2430 SDP boot broken after Linus' rmk merge) Santosh Shilimkar
2013-07-24 15:40 ` Santosh Shilimkar
2013-07-24 17:23 ` Russell King - ARM Linux
2013-07-24 17:23 ` Russell King - ARM Linux
2013-07-24 18:17 ` Santosh Shilimkar
2013-07-24 18:17 ` Santosh Shilimkar
2013-07-25 6:40 ` OMAP2430 SDP boot broken after Linus' rmk merge Tomi Valkeinen
2013-07-25 6:40 ` Tomi Valkeinen
2013-07-25 6:50 ` Tomi Valkeinen
2013-07-25 6:50 ` Tomi Valkeinen
2013-07-26 22:59 ` Russell King - ARM Linux
2013-07-26 22:59 ` Russell King - ARM Linux
2013-08-07 18:09 ` Paul Walmsley
2013-08-07 18:09 ` Paul Walmsley
2013-08-08 5:37 ` Rajendra Nayak
2013-08-08 5:37 ` Rajendra Nayak
2013-08-08 10:20 ` Rajendra Nayak
2013-08-08 10:20 ` Rajendra Nayak
2013-07-23 10:33 ` Jonathan Austin
2013-07-23 10:33 ` Jonathan Austin
2013-07-31 0:57 ` Paul Walmsley
2013-07-31 0:57 ` Paul Walmsley
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