以android 7.0为例，其他系统版本可以找到相关文件。
diff --git a/kernel/kernel/printk.c b/kernel/kernel/printk.c
old mode 100644
new mode 100755
index 7874259..c12ba60
--- a/kernel/kernel/printk.c
+++ b/kernel/kernel/printk.c
@@ -60,7 +60,7 @@ extern void printascii(char *);
/* We show everything that is MORE important than this.. */
#define MINIMUM_CONSOLE_LOGLEVEL 1 /* Minimum loglevel we let people use */
-#define DEFAULT_CONSOLE_LOGLEVEL 7 /* anything MORE serious than KERN_DEBUG */
+#define DEFAULT_CONSOLE_LOGLEVEL 0 /* anything MORE serious than KERN_DEBUG */
int console_printk[4] = {
DEFAULT_CONSOLE_LOGLEVEL, /* console_loglevel */
