diff --git a/components/newlib/README.md b/components/newlib/README.md
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+The newlib version has been updated to "2.2.0" and supply two version C libraries to user.
+One is "libc.a" which functions have more features base on stand C, another is "libc_nano.c"
+which functions have less function.
+
+You can choose the one you needed by menuconfig:
+```
+Component config --->
+        newlib --- >
+                newlib level(XXXX)
+                        ( ) normal
+                        ( ) nano
+```
+
+The normal "libc" has position argument, "long long" type data and float data
+transformation at function printf/scanf and so on. So it should cost more stack
+and heap, the test data as following:
+
+|||||||||||||||
+|--:|--:|--:|--:|--:|--:|--:|--:|--:|--:|--:|--:|--:|--:|
+||Object||Origin newlib||||New newlib||||New newlib nano|||
+|||||||||||||||
+||||Start heap/byte|53000|||Start heap/byte|49184|||Start heap/byte||51824|
+|||||||||||||||
+||Fucntion||Stack/byte|Heap/byte|Heap cost/byte||Stack/byte|Heap/byte|Heap cost/byte||Stack/byte|Heap/byte|Heap cost/byte|
+||isalnum||96|53000|0||80|49184|0||80|51824|0|
+||isalpha||80|53000|0||64|49184|0||64|51824|0|
+||isspace||80|53000|0||64|49184|0||64|51824|0|
+|||||||||||||||
+||atoi||160|53000|0||144|49184|0||144|51824|0|
+||strtol||144|53000|0||128|49184|0||128|51824|0|
+||atof||224|53000|0||208|49184|0||208|51824|0|
+||atoff||224|53000|0||208|49184|0||208|51824|0|
+||strtod||208|53000|0||192|49184|0||192|51824|0|
+||strtof||208|53000|0||192|49184|0||192|51824|0|
+|||||||||||||||
+||asprintf||880|52616|384||1200|48800|384||608|51632|192|
+||sscanf ||1552|53000|0||2032|49184|0||1120|51824|0|
+|||||||||||||||
+||gmtime||944|52616|384||1040|48576|608||1296|51512|312|
+||localtime||160|53000|0||288|49184|0||288|51824|0|
+||mktime||320|53000|0||448|49184|0||448|51824|0|
+||asctime||768|52488|480||1264|48528|656||752|51464|360|
+||settimeofday||336|53000|0||320|49184|0||320|51824|0|
+||gettimeofday||480|53000|0||464|49184|0||464|51824|0|
+||localtime_r||304|53000|0||432|49184|0||432|51824|0|
+|||||||||||||||
+||asprintf（64bit）||752|52424|576||1136|48336|848||608|51272|552|
+||sscanf（64bit）||1056|53000|0||1376|49184|0||1040|51824|0|