On Wed, Mar 02, 2016 at 09:08:46PM +0000, evan.ll...@arm.com wrote: > From: Evan Lloyd <evan.ll...@arm.com> > > Architecturally, the TTBCR register value is undefined at reset for > Non-Secure. > On some platforms the reset value for TTBCR is not zero and > this causes a data abort exception once the MMU is enabled. > > This patch configures the TTBCR register to enable translation table > walk using TTBR0.
Thanks Evan, pushed with one hopefully non-contentious modification to your updated comment (see below). > Contributed-under: TianoCore Contribution Agreement 1.0 > Signed-off-by: Evan Lloyd <evan.ll...@arm.com> > diff --git a/ArmPkg/Library/ArmLib/ArmV7/ArmV7Mmu.c > b/ArmPkg/Library/ArmLib/ArmV7/ArmV7Mmu.c > index fc8ea42..7caff5a 100644 > --- a/ArmPkg/Library/ArmLib/ArmV7/ArmV7Mmu.c > +++ b/ArmPkg/Library/ArmLib/ArmV7/ArmV7Mmu.c > @@ -1,7 +1,7 @@ > /** @file > * File managing the MMU for ARMv7 architecture > * > -* Copyright (c) 2011-2013, ARM Limited. All rights reserved. > +* Copyright (c) 2011-2016, ARM Limited. All rights reserved. > * > * This program and the accompanying materials > * are licensed and made available under the terms and conditions of the BSD > License > @@ -347,6 +347,16 @@ ArmConfigureMmu ( > > ArmSetTTBR0 ((VOID *)(UINTN)(((UINTN)TranslationTable & > ~TRANSLATION_TABLE_SECTION_ALIGNMENT_MASK) | (TTBRAttributes & 0x7F))); > > + // > + // The TTBCR register value is undefined at reset in the Non-Secure world. > + // Writing 0 has the effect of: > + // Clearing EAE: Use short descriptors, as mandated by specification. > + // Clearing PD0 and PD1: Translation Table Walk Disable is off. > + // Clearing N: Perform all translation table walks through TTBR0. > + // (0 is the default reset value, in non-secure systems.) + // (0 is the default reset value in systems not implementing + // the Security Extensions.) > + // > + ArmSetTTBCR (0); > + > ArmSetDomainAccessControl (DOMAIN_ACCESS_CONTROL_NONE(15) | > DOMAIN_ACCESS_CONTROL_NONE(14) | > DOMAIN_ACCESS_CONTROL_NONE(13) | _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel
