1. Makefile syntax alone only supports equal / not equal

2. Hence combine with shell command. E.g. to see if VAL_A > VAL_B:

   ifeq ($(shell test $(VAL_A) -gt $(VAL_B); echo $$?), 0)
     # ...DO SOMETHING...
   endif
   

   • $? designates the return value of the last shell cmd (in this case test ...)
   • $? has an extra $ sign to escape the $ for evaluation by shell
   • test returns 0 if true, else 1
   • VAL_A, VAL_B can instead be constant values

References:

• https://stackoverflow.com/a/28354572
• https://stackoverflow.com/questions/6834487/what-is-the-dollar-question-mark-variable-in-shell-scripting