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* [PATCH 1/6] ARM: Add inline function smp_on_up() for early init testing
@ 2010-08-30 21:00 Tony Lindgren
  0 siblings, 0 replies; 9+ messages in thread
From: Tony Lindgren @ 2010-08-30 21:00 UTC (permalink / raw)
  To: linux-arm-kernel

Add inline function smp_on_up() for early init checks, and
change build_mem_type_table to use it.

Signed-off-by: Tony Lindgren <tony@atomide.com>
---
 arch/arm/include/asm/smp_plat.h |   16 ++++++++++++++++
 arch/arm/mm/mmu.c               |   20 +++++++++++---------
 2 files changed, 27 insertions(+), 9 deletions(-)

diff --git a/arch/arm/include/asm/smp_plat.h b/arch/arm/include/asm/smp_plat.h
index 8db3512..5ef4114 100644
--- a/arch/arm/include/asm/smp_plat.h
+++ b/arch/arm/include/asm/smp_plat.h
@@ -39,4 +39,20 @@ static inline int cache_ops_need_broadcast(void)
 #define UP(instr...)	_str(instr)
 #endif
 
+static inline int smp_on_up(void)
+{
+#ifdef CONFIG_SMP_ON_UP
+	int smp_on_up;
+
+	asm(							\
+		SMP(mov	%0, #0)					\
+		UP(mov	%0, #1)					\
+		: "=r" (smp_on_up));
+
+	return smp_on_up;
+#else
+	return 0;
+#endif
+}
+
 #endif
diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
index 6e1c4f6..f320901 100644
--- a/arch/arm/mm/mmu.c
+++ b/arch/arm/mm/mmu.c
@@ -430,15 +430,17 @@ static void __init build_mem_type_table(void)
 		/*
 		 * Mark memory with the "shared" attribute for SMP systems
 		 */
-		user_pgprot |= L_PTE_SHARED;
-		kern_pgprot |= L_PTE_SHARED;
-		vecs_pgprot |= L_PTE_SHARED;
-		mem_types[MT_DEVICE_WC].prot_sect |= PMD_SECT_S;
-		mem_types[MT_DEVICE_WC].prot_pte |= L_PTE_SHARED;
-		mem_types[MT_DEVICE_CACHED].prot_sect |= PMD_SECT_S;
-		mem_types[MT_DEVICE_CACHED].prot_pte |= L_PTE_SHARED;
-		mem_types[MT_MEMORY].prot_sect |= PMD_SECT_S;
-		mem_types[MT_MEMORY_NONCACHED].prot_sect |= PMD_SECT_S;
+		if (!smp_on_up()) {
+			user_pgprot |= L_PTE_SHARED;
+			kern_pgprot |= L_PTE_SHARED;
+			vecs_pgprot |= L_PTE_SHARED;
+			mem_types[MT_DEVICE_WC].prot_sect |= PMD_SECT_S;
+			mem_types[MT_DEVICE_WC].prot_pte |= L_PTE_SHARED;
+			mem_types[MT_DEVICE_CACHED].prot_sect |= PMD_SECT_S;
+			mem_types[MT_DEVICE_CACHED].prot_pte |= L_PTE_SHARED;
+			mem_types[MT_MEMORY].prot_sect |= PMD_SECT_S;
+			mem_types[MT_MEMORY_NONCACHED].prot_sect |= PMD_SECT_S;
+		}
 #endif
 	}
 
-- 
1.7.1

^ permalink raw reply related	[flat|nested] 9+ messages in thread
* [PATCH 0/4] Hacks to allow booting ARM SMP kernel on UP ARMv7
@ 2010-08-17 14:12 Tony Lindgren
  2010-08-17 15:40 ` Russell King - ARM Linux
  0 siblings, 1 reply; 9+ messages in thread
From: Tony Lindgren @ 2010-08-17 14:12 UTC (permalink / raw)
  To: linux-arm-kernel

* Russell King - ARM Linux <linux@arm.linux.org.uk> [100817 16:44]:
> On Tue, Aug 17, 2010 at 01:53:12PM +0300, Tony Lindgren wrote:
> > Here are some experimental patches to allow booting ARMv7 SMP
> > kernel on UP to some extent. Posting these early in case it is
> > of any help as I know at least Bryan Wu is working on similar
> > issues.
> 
> I think these are compeltely the wrong direction.  First thing to realise
> is that XIP in the "SMP and UP in one kernel" is not really practical -
> I'm not sure that many people who want that kind of flexibility also want
> XIP too.
> 
> So let's forget about the kernel text being read-only.

OK, at least for me.
 
> The second thing to realise is that most of the SMP dependencies are in
> assembly - and we can make lists of instructions and their modified
> versions that would be necessary to boot a SMP kernel on UP.

OK cool.
 
> So something like this will do (though note that not everywhere has been
> fixed up - such as the page table flags - or this patch tested yet.)

Great, will give it a try hopefully tomorrow. Sounds like that's the way
to deal with fixing up things when booting up older UP ARMv6 without the
32v6 support :)
 
> If we don't want the SMP-on-UP support for SMP kernels (it's not actually
> all that big - around 512 bytes) then we can discard the .smpalt.init
> section and the __fixup_smp code.

OK

Regards,

Tony

^ permalink raw reply	[flat|nested] 9+ messages in thread
end of thread, other threads:[~2010-09-09  3:45 UTC | newest]

Thread overview: 9+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2010-08-30 21:00 [PATCH 1/6] ARM: Add inline function smp_on_up() for early init testing Tony Lindgren
  -- strict thread matches above, loose matches on Subject: below --
2010-08-17 14:12 [PATCH 0/4] Hacks to allow booting ARM SMP kernel on UP ARMv7 Tony Lindgren
2010-08-17 15:40 ` Russell King - ARM Linux
2010-08-19  7:38   ` Tony Lindgren
2010-08-19  9:38     ` Bryan Wu
2010-08-19  9:57       ` Tony Lindgren
2010-08-19 10:20         ` Russell King - ARM Linux
2010-08-20 12:06           ` Tony Lindgren
2010-08-30 22:55             ` Tony Lindgren
2010-09-02 13:36               ` Russell King - ARM Linux
2010-09-02 16:16                 ` Tony Lindgren
2010-09-02 16:18                   ` [PATCH 1/6] ARM: Add inline function smp_on_up() for early init testing Tony Lindgren
2010-09-02 17:08                     ` Russell King - ARM Linux
2010-09-02 17:42                       ` Tony Lindgren
2010-09-03 12:09                         ` Shilimkar, Santosh
2010-09-06 10:17                           ` Bryan Wu
2010-09-08  3:26                             ` Tony Lindgren
2010-09-08 20:26                               ` Tony Lindgren
2010-09-09  3:45                                 ` Bryan Wu

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