Working with a Headless Raspberry PI 4 with an Ubuntu Server 18.04.4 LTS.. I am trying to configure the source kernel. I have installed libncurses-dev, kernel-package, qt4-dev-tools.
When I run 'make menuconfig' in the directory /linux-5.7, it shows:
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: *** [scripts/kconfig/lexer.lex.c] Error 127 Makefile:588: recipe for target 'menuconfig' failed make: *** [menuconfig] Error 2
Lost on what to do, everything I have read hasn't helped so far. My goal is to start programming device drivers, and to do so I need a configured and built kernel source tree on disk.