diff --git a/am/src/xs/isa/riscv/cache.c b/am/src/xs/isa/riscv/cache.c
index 5c816bea..d02d6ce8 100644
--- a/am/src/xs/isa/riscv/cache.c
+++ b/am/src/xs/isa/riscv/cache.c
@@ -3,6 +3,19 @@
 #include <pmp.h>
 #include <klib.h>
 
+// these functions are interface for cache
+// uintptr_t _l1cache_op_read(int op_idx): return value in the cache cop csr
+// uintptr_t _l1cache_data_read(int data_idx): return data in the cache data csr
+// void _l1cache_op_write(int op_idx, uintptr_t val): set value in the cache cop csr
+// void _l1cache_data_write(int data_idx, uintptr_t val): set data in the cache data csr
+// when testing, can use these interface in nexus-am/tests/amtest/src/tests/cache.c
+
+// void _l3cache_tag(int tag): set value of tag in l3chache
+// void _l3cache_set(int set): set value of tag in l3chache
+// void _l3cache_cmd(int cmd): set value of tag in l3chache
+// when testing, can use these interface in nexus-am/tests/dualcoretest/tests/huancunop.c
+
+
 uintptr_t _l1cache_op_read(int op_idx) {
     uintptr_t op;
     switch(op_idx){
diff --git a/am/src/xs/isa/riscv/pma.c b/am/src/xs/isa/riscv/pma.c
index 00ad29ab..8f73de59 100644
--- a/am/src/xs/isa/riscv/pma.c
+++ b/am/src/xs/isa/riscv/pma.c
@@ -2,11 +2,11 @@
 #include <pmp.h>
 #include <klib.h>
 
-// this functions are interface for pma
-// _pma_get_addr(int addr_idx): return value in the pmpaddr csr
-// _pma_get_cfg(int cfg_idx): return value in the pmpefg csr
-// _pma_set_addr(int addr_idx, uintptr_t val): modify value in the pmpaddr csr
-// _pma_set_cfg(int cfg_idx, uintptr_t val): modify value in the pmpcfg csr
+// these functions are interface for pma
+// uintptr_t _pma_get_addr(int addr_idx): return value in the pmpaddr csr
+// uintptr_t _pma_get_cfg(int cfg_idx): return value in the pmpefg csr
+// void _pma_set_addr(int addr_idx, uintptr_t val): modify value in the pmpaddr csr
+// void _pma_set_cfg(int cfg_idx, uintptr_t val): modify value in the pmpcfg csr
 // when testing pma:
 // firstly,  using  _cfg = _pma_get_cfg(cfg_idx), get the value of cfg
 // secondly, using _cfg = _cfg | PMP_W, or using _cfg = _cfg & ~PMP_W, to set the permission