通过关闭kenrel一些宏定义优化开机速度
CONFIG_BLK_DEV_LOOP=y
Loopback device support
CONFIG_SERIAL_MSM_HS=y
CONFIG_SERIAL_MSM_HSL=y
CONFIG_SERIAL_MSM_HSL_CONSOLE=y
By enabling these configs, it is possible to enable it’s onboard high-speed serial port for machine, based on the MSM™ chipset family of SoCs
CONFIG_CC_OPTIMIZE_FOR_SIZE=y
By disabling this config, boot time improvement of ~ 100 ms
As it causes GCC to generate jump-to-jump code, which causes cache line bouncing and hurting performance, disable this config
CONFIG_RMNET_DATA_DEBUG_PKT
Enable debug for RmNet data to support MAP data feature for data connectivity
CONFIG_DEBUG_SET_MODULE_RONX
Sets loadable kernel module data as no execute (NX) and text as read only (RO)
特别说一下CONFIG_CC_OPTIMIZE_FOR_SIZE：
需要修改makefile和pef config。
else
-KBUILD_CFLAGS += -O2
+KBUILD_CFLAGS += -O2 $(call cc-disable-warning,maybe-uninitialized,)
endif
-CONFIG_CC_OPTIMIZE_FOR_SIZE=y
+#CONFIG_CC_OPTIMIZE_FOR_SIZE=y