[U-Boot] [PATCH v3 12/14] MIPS: Ensure Config.K0=2 applies before any memory accesses

[Paul Burton]

During boot we set Config.K0=2 (uncached) such that any accesses to the
kseg0 memory region are performed uncached before the caches are
initialised. This write to the Config register introduces an execution
hazard between it & any following memory accesses (such as the load of
_gp), which we need to clear in order to ensure those memory accesses
are actually performed uncached. Clear this execution hazard with the
insertion of an ehb execution hazard barrier instruction.

Signed-off-by: Paul Burton <paul.burton at imgtec.com>

---

Changes in v3:
- New patch

Changes in v2: None

 arch/mips/cpu/start.S | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/mips/cpu/start.S b/arch/mips/cpu/start.S
index c157d03..8f85ede 100644
--- a/arch/mips/cpu/start.S
+++ b/arch/mips/cpu/start.S
@@ -127,6 +127,7 @@ reset:
 	and	t0, t0, MIPS_CONF_IMPL
 	or	t0, t0, CONF_CM_UNCACHED
 	mtc0	t0, CP0_CONFIG
+	ehb
 #endif
 
 	/*
-- 
2.10.0