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
@@ -125,6 +125,21 @@ are carried through to the underlying file.
to the underlying file requires the use of
.BR msync (2).)
+The same as
+mappings ignore unknown flags in
+.IR flags .
+In contrast when creating mapping of
+mapping type, the kernel verifies all passed flags are known and fails the
+otherwise. This mapping type is also required to be able to use some mapping
Create a private copy-on-write mapping.
Updates to the mapping are not visible to other processes
@@ -352,6 +367,21 @@ option.
Because of the security implications,
that option is normally enabled only on embedded devices
(i.e., devices where one has complete control of the contents of user memory).
+.BR MAP_SYNC " (since Linux 4.15)"
+This flags is available only with
+mapping type. Mappings of
+type will silently ignore this flag.
+This flag is supported only for files supporting DAX (direct mapping of persistent
+memory). For other files, creating mapping with this flag results in
+error. Shared file mappings with this flag provide the guarantee that while
+some memory is writeably mapped in the address space of the process, it will
+be visible in the same file at the same offset even after the system crashes or
+is rebooted. This allows users of such mappings to make data modifications
+persistent in a more efficient way using appropriate CPU instructions.
Of the above flags, only