```man
reboot(2) System Calls Manual
NAME
reboot
LIBRARY
Standard C library (libc, -lc)
DESCRIPTION
...
This system call fails (with the error EINVAL)
unless magic equals LINUX_REBOOT_MAGIC1 (that is, 0xfee1dead)
and magic2 equals LINUX_REBOOT_MAGIC2 (that is, 0x28121969).
However, since Linux 2.1.17 also LINUX_REBOOT_MAGIC2A
(that is, 0x05121996) and since Linux 2.1.97 also
LINUX_REBOOT_MAGIC2B (that is, 0x16041998) and
since Linux 2.5.71 also LINUX_REBOOT_MAGIC2C
(that is, 0x20112000) are permitted as values
for magic2. (The hexadecimal values of these
constants are meaningful.)
```