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From: tony@atomide.com (Tony Lindgren)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] arm: Fix mounting root on omaps with CPU_V6 and CPU_V7
Date: Mon, 15 Mar 2010 15:25:43 -0700	[thread overview]
Message-ID: <mailman.239.1268848572.2170.linux-arm-kernel@lists.infradead.org> (raw)

To mount root on omap2420, we need to disable VFPv3 and
HAS_TLS_REG.

VFPv3 is only available on CPU_V7. TLS_REG is only available
on ARM11 starting with r1p0 and later. As omap2420 is r0p2,
it does not have TLS_REG.

Otherwise we'll get something like this for CPUv3:

Freeing init memory: 184K
Internal error: Oops - undefined instruction: 0 [#1]
last sysfs file:
Modules linked in:
CPU: 0    Not tainted  (2.6.33-rc8-07824-gf2e1d91-dirty #36)
PC is at no_old_VFP_process+0x8/0x3c
LR is at __und_usr_unknown+0x0/0x14
...

Or the system just hangs if HAS_TLS_REG is set.

Signed-off-by: Tony Lindgren <tony@atomide.com>

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index d97d893..409ae23 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1549,7 +1549,7 @@ config VFP
 config VFPv3
 	bool
 	depends on VFP
-	default y if CPU_V7
+	default y if CPU_V7 && !CPU_V6
 
 config NEON
 	bool "Advanced SIMD (NEON) Extension support"
diff --git a/arch/arm/mm/Kconfig b/arch/arm/mm/Kconfig
index c4ed9f9..ff0c829 100644
--- a/arch/arm/mm/Kconfig
+++ b/arch/arm/mm/Kconfig
@@ -718,11 +718,11 @@ config TLS_REG_EMUL
 config HAS_TLS_REG
 	bool
 	depends on !TLS_REG_EMUL
-	default y if SMP || CPU_32v7
+	default y if (SMP || CPU_32v7) && !ARCH_OMAP2
 	help
 	  This selects support for the CP15 thread register.
-	  It is defined to be available on some ARMv6 processors (including
-	  all SMP capable ARMv6's) or later processors.  User space may
+	  It is defined to be available on some ARMv6 processors (r1p0 and
+	  later, including all SMP capable ARMv6's).  User space may
 	  assume directly accessing that register and always obtain the
 	  expected value only on ARMv7 and above.
 

--HTLCc13+3hfAZ6SL--

             reply	other threads:[~2010-03-15 22:25 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-03-15 22:25 Tony Lindgren [this message]
  -- strict thread matches above, loose matches on Subject: below --
2010-03-17 17:57 [PATCH] arm: Fix mounting root on omaps with CPU_V6 and CPU_V7 Tony Lindgren
2010-03-17 18:07 ` Catalin Marinas
2010-03-17 19:11   ` Tony Lindgren
2010-03-18 11:13     ` Catalin Marinas
2010-03-18 17:00       ` Tony Lindgren

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