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mmap.2: Minor tweaks to Jan Kara's patch 

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
This commit is contained in:
Michael Kerrisk 2018-04-12 14:49:52 +02:00
parent b138773b1e
commit 79da08c844
1 changed files with 18 additions and 13 deletions
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31
man2/mmap.2
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@ -127,19 +127,21 @@ to the underlying file requires the use of
.BR msync (2).) .BR msync (2).)
.TP .TP
.BR MAP_SHARED_VALIDATE " (since Linux 4.15)" .BR MAP_SHARED_VALIDATE " (since Linux 4.15)"
The same as This flag provides the same behavior as
.B MAP_SHARED .B MAP_SHARED
except that except that
.B MAP_SHARED .B MAP_SHARED
mappings ignore unknown flags in mappings ignore unknown flags in
.IR flags . .IR flags .
In contrast when creating mapping of By contrast, when creating a mapping using
.B MAP_SHARED_VALIDATE .B MAP_SHARED_VALIDATE ,
mapping type, the kernel verifies all passed flags are known and fails the the kernel verifies all passed flags are known and fails the
mapping with mapping with the error
.BR EOPNOTSUPP .BR EOPNOTSUPP
otherwise. for unknown flags.
This mapping type is also required to be able to use some mapping flags. This mapping type is also required to be able to use some mapping flags
(e.g.,
.BR MAP_SYNC ).
.TP .TP
.B MAP_PRIVATE .B MAP_PRIVATE
Create a private copy-on-write mapping. Create a private copy-on-write mapping.
@ -155,6 +157,8 @@ Both
and and
.B MAP_PRIVATE .B MAP_PRIVATE
are described in POSIX.1-2001 and POSIX.1-2008. are described in POSIX.1-2001 and POSIX.1-2008.
.B MAP_SHARED_VALIDATE
is a Linux extension.
.PP .PP
In addition, zero or more of the following values can be ORed in In addition, zero or more of the following values can be ORed in
.IR flags : .IR flags :
@ -432,19 +436,20 @@ support can later be transparently implemented for glibc.
.\" context switch optimization?" .\" context switch optimization?"
.TP .TP
.BR MAP_SYNC " (since Linux 4.15)" .BR MAP_SYNC " (since Linux 4.15)"
This flags is available only with This flag is available only with the
.B MAP_SHARED_VALIDATE .B MAP_SHARED_VALIDATE
mapping type. mapping type;
Mappings of mappings of type
.B MAP_SHARED .B MAP_SHARED
type will silently ignore this flag. will silently ignore this flag.
This flag is supported only for files supporting DAX This flag is supported only for files supporting DAX
(direct mapping of persistent memory). (direct mapping of persistent memory).
For other files, creating mapping with this flag results in For other files, creating a mapping with this flag results in an
.B EOPNOTSUPP .B EOPNOTSUPP
error. error.
.IP
Shared file mappings with this flag provide the guarantee that while Shared file mappings with this flag provide the guarantee that while
some memory is writeably mapped in the address space of the process, some memory is writably mapped in the address space of the process,
it will be visible in the same file at the same offset even after it will be visible in the same file at the same offset even after
the system crashes or is rebooted. the system crashes or is rebooted.
This allows users of such mappings to make data modifications This allows users of such mappings to make data modifications