diff options
Diffstat (limited to 'lib/libc/sys/mmap.2')
| -rw-r--r-- | lib/libc/sys/mmap.2 | 26 |
1 files changed, 13 insertions, 13 deletions
diff --git a/lib/libc/sys/mmap.2 b/lib/libc/sys/mmap.2 index e9eb9d3..f4cb27e 100644 --- a/lib/libc/sys/mmap.2 +++ b/lib/libc/sys/mmap.2 @@ -137,7 +137,7 @@ Region is not included in a core file. .It Dv MAP_NOSYNC Causes data dirtied via this VM map to be flushed to physical media only when necessary (usually by the pager) rather then gratuitously. -Typically this prevents the update daemons from flushing pages dirtied +Typically this prevents the update daemons from flushing pages dirtied through such maps and thus allows efficient sharing of memory across unassociated processes using a file-backed shared memory map. Without this option any VM pages you dirty may be flushed to disk every so often @@ -193,7 +193,7 @@ The .Xr msync 2 system call is obsolete since .Bx -implements a coherent filesystem buffer cache. However, it may be +implements a coherent filesystem buffer cache. However, it may be used to associate dirty VM pages with filesystem buffers and thus cause them to be flushed to physical media sooner rather then later. .It Dv MAP_PRIVATE @@ -217,26 +217,26 @@ to enable this option for other architechures. implies .Dv MAP_ANON , and -.Fa offset -of 0. -.Fa fd -must be -1 and -.Fa prot +.Fa offset +of 0. +.Fa fd +must be -1 and +.Fa prot must include at least .Dv PROT_READ and .Dv PROT_WRITE . This option creates -a memory region that grows to at most -.Fa len +a memory region that grows to at most +.Fa len bytes in size, starting from the stack top and growing down. The -stack top is the starting address returned by the call, plus -.Fa len +stack top is the starting address returned by the call, plus +.Fa len bytes. The bottom of the stack at maximum growth is the starting address returned by the call. .El .Pp -The +The .Xr close 2 function does not unmap pages, see .Xr munmap 2 @@ -332,7 +332,7 @@ was specified and insufficient memory was available. .Sh BUGS .Fa len is limited to 2GB. Mmapping slightly more than 2GB doesn't work, but -it is possible to map a window of size (filesize % 2GB) for file sizes +it is possible to map a window of size (filesize % 2GB) for file sizes of slightly less than 2G, 4GB, 6GB and 8GB. .Pp The limit is imposed for a variety of reasons. |
