diff options
| -rw-r--r-- | lib/libc/sys/mmap.2 | 30 |
1 files changed, 8 insertions, 22 deletions
diff --git a/lib/libc/sys/mmap.2 b/lib/libc/sys/mmap.2 index f4c0b42..57f669f 100644 --- a/lib/libc/sys/mmap.2 +++ b/lib/libc/sys/mmap.2 @@ -350,29 +350,15 @@ sysctl. The .Fa len argument -is limited to 2GB. -Mmapping slightly more than 2GB does not work, but -it is possible to map a window of size (filesize % 2GB) for file sizes -of slightly less than 2G, 4GB, 6GB and 8GB. +is limited to the maximum file size or available userland address +space. +Files may not be able to be made more than 1TB large on 32 bit systems +due to file systems restrictions and bugs, but address space is far more +restrictive. Larger files may be possible on 64 bit systems. .Pp -The limit is imposed for a variety of reasons. -Most of them have to do -with -.Fx -not wanting to use 64 bit offsets in the VM system due to -the extreme performance penalty. -So -.Fx -uses 32bit page indexes and -this gives -.Fx -a maximum of 8TB filesizes. -It is actually bugs in -the file system code that causes the limit to be further restricted to -1TB (loss of precision when doing blockno calculations). -.Pp -Another reason for the 2GB limit is that file system metadata can -reside at negative offsets. +The previous documented limit of 2GB was a documentation bug. +That limit has not existed since +.Fx 2.2 . .Pp Note that an attempt to .Fn mmap |
