Re: [PATCH] mmap.2: Add description of MAP_SHARED_VALIDATE and MAP_SYNC
On Thu, Oct 19, 2017 at 02:58:17PM +0200, Jan Kara wrote:
Signed-off-by: Jan Kara <jack(a)suse.cz>
---
man2/mmap.2 | 30 ++++++++++++++++++++++++++++++
1 file changed, 30 insertions(+)
diff --git a/man2/mmap.2 b/man2/mmap.2
index 47c3148653be..598ff0c64f7f 100644
--- a/man2/mmap.2
+++ b/man2/mmap.2
@@ -125,6 +125,21 @@ are carried through to the underlying file.
to the underlying file requires the use of
.BR msync (2).)
.TP
+.B MAP_SHARED_VALIDATE
+The same as
+.B MAP_SHARED
+except that
+.B MAP_SHARED
+mappings ignore unknown flags in
+.IR flags .
+In contrast when creating mapping of
+.B MAP_SHARED_VALIDATE
+mapping type, the kernel verifies all passed flags are known and fails the
+mapping with
+.BR EOPNOTSUPP
+otherwise. This mapping type is also required to be able to use some mapping
+flags.
+.TP
Some small nits:
I think you should maybe include a "(since Linux 4.15)" type note after the
MAP_SHARED_VALIDATE header. You also need to update the following line:
Both of these flags are described in POSIX.1-2001 and POSIX.1-2008.
Which used to refer to MAP_SYNC and MAP_PRIVATE.