include/generated/compile.h is generated by scripts/mkcompile_h and defines four macros: #define UTS_MACHINE "x86_64" #define LINUX_COMPILE_BY "rene" #define LINUX_COMPILE_HOST "appletree" #define LINUX_COMPILER "gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2"
linux_banner (defined and/or declared in init/version-timestamp.c and init/version.c).