The mprotect.2 NOTES say:
On systems that do not support protection keys in
hardware, pkey_mprotect() may still be used, but pkey must
be set to 0. When called this way, the operation of
pkey_mprotect() is equivalent to mprotect().
But this is not what the glibc manual says:
It is also possible to call pkey_mprotect with a key value
of -1, in which case it will behave in the same way as
mprotect.
Which is correct. Both the glibc implementation and the
kernel check whether pkey is -1. 0 is not a valid pkey when
memory protection keys are not supported in hardware.
Signed-off-by: Mark Wielaard <mark@klomp.org>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
.BR pkey_mprotect ()
may still be used, but
.IR pkey
-must be set to 0.
+must be set to -1.
When called this way, the operation of
.BR pkey_mprotect ()
is equivalent to