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-rw-r--r--src/soc/intel/common/block/cpu/car/cache_as_ram.S17
1 files changed, 17 insertions, 0 deletions
diff --git a/src/soc/intel/common/block/cpu/car/cache_as_ram.S b/src/soc/intel/common/block/cpu/car/cache_as_ram.S
index 29bd3fe87f..74957aba9f 100644
--- a/src/soc/intel/common/block/cpu/car/cache_as_ram.S
+++ b/src/soc/intel/common/block/cpu/car/cache_as_ram.S
@@ -221,6 +221,23 @@ setup_car_mtrr:
is_bootguard_nem
jz no_bootguard_car_continue
+ /*
+ * With Bootguard some RO caching of the flash is already set up by
+ * the ACM. It looks like in such a setup 'clear_car' will not properly fill
+ * the cachelines. Fill all the CAR cachelines explicitly using sfence.
+ * This assumes 64 bytes cachelines.
+ */
+ movl $CONFIG_DCACHE_RAM_BASE, %edi
+ movl $CONFIG_DCACHE_RAM_SIZE, %ecx
+ shr $0x06, %ecx
+ xor %eax, %eax
+
+1:
+ movl %eax, (%edi)
+ sfence
+ add $64, %edi
+ loop 1b
+
clear_car
jmp car_init_done