The Makefile.kernio file tests the following environment variables:
CPUBOARD | Set to the type of CPU used in the target system, for example IP19 or IP22. |
COMPILATION_MODEL | Set to 64 for a 64-bit kernel module, or to 32 for a 32-bit kernel module. |
The purpose of the rules in Makefile.kernio is to set compiler variables and compiler options into a Make variable CFLAGS. Other Make variables would be set by your own Makefile.
Note: Makefile.kernio is designed for nonloadable drivers. In particular it sets the compiler option -G8, which is valid for nonloadable drivers. A loadable driver must use -G0.