Module Name: src
Committed By: rin
Date: Mon Aug 26 17:18:42 UTC 2019
Modified Files:
src/sys/arch/arm/conf: Makefile.arm
Log Message:
PR kern/54486
Workaround for alignment faults on ARMv6+, at least occur with
axe(4) and athn(4) drivers.
For ARMv6+, unaligned access is enabled by default. However, it
cannot be used for non-cacheable memory, which is used as DMA
buffers. This results in alignment faults above. A real fix is
to use cacheable memory as DMA buffers. However, it breaks some
drivers, awge(4) and vchiq(4) at least.
Until we figure out problems and fix them, we choose a fail-safe
workaround here; forbid unaligned memory access for whole kernel.
Affects on performance is negligibly small as far as we can see.
XXX
pullup netbsd-9
To generate a diff of this commit:
cvs rdiff -u -r1.49 -r1.50 src/sys/arch/arm/conf/Makefile.arm
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/arch/arm/conf/Makefile.arm
diff -u src/sys/arch/arm/conf/Makefile.arm:1.49 src/sys/arch/arm/conf/Makefile.arm:1.50
--- src/sys/arch/arm/conf/Makefile.arm:1.49 Sat Sep 22 12:24:01 2018
+++ src/sys/arch/arm/conf/Makefile.arm Mon Aug 26 17:18:42 2019
@@ -1,4 +1,4 @@
-# $NetBSD: Makefile.arm,v 1.49 2018/09/22 12:24:01 rin Exp $
+# $NetBSD: Makefile.arm,v 1.50 2019/08/26 17:18:42 rin Exp $
# Makefile for NetBSD
#
@@ -53,6 +53,26 @@ CPPFLAGS.cpufunc_asm_armv6.S+= -mcpu=arm
CPPFLAGS.cpufunc_asm_arm11.S+= -mcpu=arm1136j-s
CPPFLAGS.cpufunc_asm_xscale.S+= -mcpu=xscale
+.if !empty(MACHINE_ARCH:Mearmv6*) || !empty(MACHINE_ARCH:Mearmv7*)
+# XXX
+#
+# Workaround for alignment faults on ARMv6+, at least occur with
+# axe(4) and athn(4) drivers.
+#
+# For ARMv6+, unaligned access is enabled by default. However, it
+# cannot be used for non-cacheable memory, which is used as DMA
+# buffers. This results in alignment faults above. A real fix is
+# to use cacheable memory as DMA buffers. However, it breaks some
+# drivers, awge(4) and vchiq(4) at least.
+#
+# Until we figure out problems and fix them, we choose a fail-safe
+# workaround here; forbid unaligned memory access for whole kernel.
+# Affects on performance is negligibly small as far as we can see.
+#
+# See PR kern/54486 for more details.
+CFLAGS+= -mno-unaligned-access
+.endif
+
##
## (3) libkern and compat
##
