failed to run /usr/bin/make [make olddefconfig]: exit status 2
  YACC    scripts/kconfig/zconf.tab.c
  LEX     scripts/kconfig/zconf.lex.c
/bin/sh: 1: flex: not found
scripts/Makefile.lib:204: recipe for target 'scripts/kconfig/zconf.lex.c' failed
make[1]: *** [scripts/kconfig/zconf.lex.c] Error 127
Makefile:506: recipe for target 'olddefconfig' failed
make: *** [olddefconfig] Error 2