Illumos kernel preprocessor macro

Question

I can't find any info on what macro to use in an ifdef to determine the illumos kernel. I use __linux to catch Linux.

Filler for stackoverflow grammar check filler filler filler filler.

Answer 1

Illumos based kernels such as SmartOS and OpenIndiana use __sun and it is sometimes suggested to check for both __sun and __SVR4.

[root@mysmartostestzone ~]# uname -a
SunOS mysmartostestzone 5.11 joyent_20170202T033902Z i86pc i386 i86pc Solaris

[root@mysmartostestzone ~]# cat test.c
#include <stdio.h>

int
main(int argc, char **argv)
{
#ifdef sun
printf("sun\n");
#endif

#ifdef __sun
printf("__sun\n");
#endif

#if defined(__sun) && defined(__SVR4)
printf("__sun && __SVR4\n");
#endif
}

[root@mysmartostestzone ~]# cc test.c

[root@mysmartostestzone ~]# ./a.out
sun
__sun
__sun && __SVR4

Update:

There will soon be an __illumos__ macro: https://www.illumos.org/issues/13726