diff options
Diffstat (limited to 'lib/libc/sys/mmap.2')
| -rw-r--r-- | lib/libc/sys/mmap.2 | 20 |
1 files changed, 19 insertions, 1 deletions
diff --git a/lib/libc/sys/mmap.2 b/lib/libc/sys/mmap.2 index 1c0d84a..2ca868e 100644 --- a/lib/libc/sys/mmap.2 +++ b/lib/libc/sys/mmap.2 @@ -207,4 +207,22 @@ was specified and insufficient memory was available. .Xr munmap 2 , .Xr mprotect 2 , .Xr madvise 2 , -.Xr mincore 2 +.Xr mincore 2 , +.Xr mlock 2 , +.Xr munlock 2 + +.Sh BUGS +.Ar len +is limit to 2GB. Mmapping slightly more than 2GB doesn't work, but +mapping a window of size (filesize % 2GB) for file sizes of slightly +less than 2G, 4GB, 6GB and 8GB. + +The limit is imposed for a variety of reasons. Most of them have to do +with FreeBSD not wanting to use 64 bit offsets in the VM system due to +the extreme performance penalty. So FreeBSD use 32bit page indexes and +this gives FreeBSD a maximum of 8TB filesizes. It's actually bugs in +the filesystem code that causes the limit to be further restricted to +1TB (loss of precision when doing blockno calculations). + +Another reason for the 2GB limit is that filesystem metadata can +reside at negative offsets. |
