prctl.2: Clarify the unsupported hardware case of EINVAL

prctls that are architecture-specific won't work on other
architectures, and arch-specific prctls that manipulate optional
hardware features likewise won't work if that hardware feature is
not present.

The established pattern seems to be to treat such prctls as if they
are unimplemented, when attempted on the wrong hardware.

Cover these cases with some generic weasel words in the closet
existing EINVAL clause.

Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>

diff --git a/man2/prctl.2 b/man2/prctl.2
index 6de4439381272ecbf322ebdfabf8a6c9cab330c0..7e78fc3c11fda958d6a43571fb6d3124a33e2dd3 100644 (file)
--- a/man2/prctl.2
+++ b/man2/prctl.2
@@ -1586,7 +1586,8 @@ is an invalid address.
 .B EINVAL
 The value of
 .I option
-is not recognized.
+is not recognized,
+or not supported on this system.
 .TP
 .B EINVAL
 .I option