Hi, I know this is trivial, but an extra "o" character here might be worth the slight improvement in readability:
Index: src/sys/arch/amd64/stand/libsa/memprobe.c =================================================================== RCS file: /cvs/src/sys/arch/amd64/stand/libsa/memprobe.c,v retrieving revision 1.17 diff -u -p -u -r1.17 memprobe.c --- src/sys/arch/amd64/stand/libsa/memprobe.c 10 Jun 2016 18:36:06 -0000 1.17 +++ src/sys/arch/amd64/stand/libsa/memprobe.c 21 Apr 2018 06:10:13 -0000 @@ -309,7 +309,7 @@ memprobe(void) extmem = 4 * 1024 * 1024 - 1024; /* Check if gate A20 is on */ - printf("a20=o%s] ", checkA20()? "n" : "ff!"); + printf("a20=%s] ", checkA20() ? "on" : "off!"); } #endif