Where are SHMMIN and SHMMAX of shmget(2) defined?

[Adhemerval Zanella]

On 12/04/2021 14:27, Peng Yu via Libc-help wrote:
> Hi,
> 
> shmget(2) mentions SHMMIN and SHMMAX.
> 
> But I don't see where they are defined and what their values are. Does
> anybody know where they are defined?
> 
> gcc -E -dD - <<< '#include <sys/shm.h>' | grep 'SHMMAX\|SHMMIN'
> 

They are provided by the kernel headers since it is system specific
and glibc does not define them as extensions:

| $ gcc -E -dD - <<< '#include <linux/shm.h>' | grep 'SHMMAX\|SHMMIN'
| #define SHMMIN 1
| #define SHMMAX (ULONG_MAX - (1UL << 24))