Hi all, Here's an updated version of this patch with more details. Looks like VFPv3 is only available on V7: http://www.arm.com/products/processors/technologies/vector-floating-point.php HAS_TLS reg is only on ARM11 starting with r1p0: http://infocenter.arm.com/help/topic/com.arm.doc.ddi0211k/Babeihid.html So that explains why it won't work on omap2420 as it's r0p2. Regards, Tony
>From adebf62d18a03ed26ec20f95860976f80690e9f1 Mon Sep 17 00:00:00 2001 From: Tony Lindgren <tony@xxxxxxxxxxx> Date: Mon, 15 Mar 2010 15:25:43 -0700 Subject: [PATCH] arm: Fix mounting root on omaps with CPU_V6 and CPU_V7 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@xxxxxxxxxxx> 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.
