linux-内核导入配置 lexer.lex.c错误

wu@ubuntu:~/linux-5.4.8$ make exynos_defconfig
HOSTCC scripts/basic/fixdep
HOSTCC scripts/kconfig/conf.o
HOSTCC scripts/kconfig/confdata.o
HOSTCC scripts/kconfig/expr.o
LEX scripts/kconfig/lexer.lex.c
/bin/sh: 1: flex: not found
scripts/Makefile.host:9: recipe for target ‘scripts/kconfig/lexer.lex.c’ failed
make[1]: *** [scripts/kconfig/lexer.lex.c] Error 127
Makefile:567: recipe for target ‘exynos_defconfig’ failed
make: *** [exynos_defconfig] Error 2

解决方法：
sudo apt-get install bison
sudo apt-get install flex