fuse.4: ffix

[thirdparty/man-pages.git] / man2 / memfd_create.2

diff --git a/man2/memfd_create.2 b/man2/memfd_create.2
index 230aab71a19e1416b60710949f9eb08fdeb9b65f..3cd392d1b4d915a0cf470880964af7d94fb04b3e 100644 (file)
--- a/man2/memfd_create.2
+++ b/man2/memfd_create.2
@@ -18,16 +18,15 @@
 .\" <http://www.gnu.org/licenses/>.
 .\" %%%LICENSE_END
 .\"
-.TH MEMFD_CREATE 2 2016-10-08 Linux "Linux Programmer's Manual"
+.TH MEMFD_CREATE 2 2018-02-02 Linux "Linux Programmer's Manual"
 .SH NAME
 memfd_create \- create an anonymous file
 .SH SYNOPSIS
-.B #include <sys/memfd.h>
+.nf
+.BR "#define _GNU_SOURCE" "         /* See feature_test_macros(7) */"
+.B #include <sys/mman.h>
 .PP
 .BI "int memfd_create(const char *" name ", unsigned int " flags ");"
-.PP
-.IR Note :
-There is no glibc wrapper for this system call; see NOTES.
 .SH DESCRIPTION
 .BR memfd_create ()
 creates an anonymous file and returns a file descriptor that refers to it.
@@ -100,6 +99,35 @@ If this flag is not set, the initial set of seals will be
 meaning that no other seals can be set on the file.
 .\" FIXME Why is the MFD_ALLOW_SEALING behavior not simply the default?
 .\" Is it worth adding some text explaining this?
+.TP
+.BR MFD_HUGETLB " (since Linux 4.14)"
+.\" commit 749df87bd7bee5a79cef073f5d032ddb2b211de8
+The anonymous file will be created in the hugetlbfs filesystem using
+huge pages.
+See the Linux kernel source file
+.I Documentation/admin-guide/mm/hugetlbpage.rst
+for more information about hugetlbfs.
+.\" commit 47b9012ecdc747f6936395265e677d41e11a31ff
+Specifying both
+.B MFD_HUGETLB
+and
+.B MFD_ALLOW_SEALING
+in
+.I flags
+is supported since Linux 4.16.
+.TP
+.BR MFD_HUGE_2MB ", " MFD_HUGE_1GB ", " "..."
+Used in conjunction with
+.B MFD_HUGETLB
+to select alternative hugetlb page sizes (respectively, 2\ MB, 1\ GB, ...)
+on systems that support multiple hugetlb page sizes.
+Definitions for known
+huge page sizes are included in the header file
+.I <linux/memfd.h>.
+.IP
+For details on encoding huge page sizes not included in the header file,
+see the discussion of the similarly named constants in
+.BR mmap (2).
 .PP
 Unused bits in
 .I flags
@@ -141,11 +169,23 @@ The address in
 points to invalid memory.
 .TP
 .B EINVAL
-An unsupported value was specified in one of the arguments:
 .I flags
-included unknown bits, or
+included unknown bits.
+.TP
+.B EINVAL
 .I name
 was too long.
+(The limit is
+.\" NAME_MAX - strlen("memfd:")
+249 bytes, excluding the terminating null byte.)
+.TP
+.B EINVAL
+Both
+.B MFD_HUGETLB
+and
+.B MFD_ALLOW_SEALING
+were specified in
+.IR flags .
 .TP
 .B EMFILE
 The per-process limit on the number of open file descriptors has been reached.
@@ -158,14 +198,13 @@ There was insufficient memory to create a new anonymous file.
 .SH VERSIONS
 The
 .BR memfd_create ()
-system call first appeared in Linux 3.17.
+system call first appeared in Linux 3.17;
+glibc support was added in version 2.27.
 .SH CONFORMING TO
 The
 .BR memfd_create ()
 system call is Linux-specific.
 .SH NOTES
-Glibc does not provide a wrapper for this system call; call it using
-.BR syscall (2).
 .PP
 .\" See also http://lwn.net/Articles/593918/
 .\" and http://lwn.net/Articles/594919/ and http://lwn.net/Articles/591108/
@@ -359,7 +398,8 @@ Existing seals: WRITE SHRINK
 .SS Program source: t_memfd_create.c
 \&
 .EX
-#include <sys/memfd.h>
+#define _GNU_SOURCE
+#include <sys/mman.h>
 #include <fcntl.h>
 #include <stdlib.h>
 #include <unistd.h>
@@ -441,7 +481,8 @@ main(int argc, char *argv[])
 .SS Program source: t_get_seals.c
 \&
 .EX
-#include <sys/memfd.h>
+#define _GNU_SOURCE
+#include <sys/mman.h>
 #include <fcntl.h>
 #include <unistd.h>
 #include <stdlib.h>