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Diffstat (limited to 'man2/mmap.2')
| -rw-r--r-- | man2/mmap.2 | 102 |
1 files changed, 52 insertions, 50 deletions
diff --git a/man2/mmap.2 b/man2/mmap.2 index 6a9395d2c2..04f117e02d 100644 --- a/man2/mmap.2 +++ b/man2/mmap.2 @@ -665,41 +665,7 @@ T} Thread safety MT-Safe .hy .ad .sp 1 -.SH STANDARDS -POSIX.1-2001, POSIX.1-2008, SVr4, 4.4BSD. -.\" SVr4 documents additional error codes ENXIO and ENODEV. -.\" SUSv2 documents additional error codes EMFILE and EOVERFLOW. -.PP -On POSIX systems on which -.BR mmap (), -.BR msync (2), -and -.BR munmap () -are available, -.B _POSIX_MAPPED_FILES -is defined in \fI<unistd.h>\fP to a value greater than 0. -(See also -.BR sysconf (3).) -.\" POSIX.1-2001: It shall be defined to -1 or 0 or 200112L. -.\" -1: unavailable, 0: ask using sysconf(). -.\" glibc defines it to 1. -.SH NOTES -Memory mapped by -.BR mmap () -is preserved across -.BR fork (2), -with the same attributes. -.PP -A file is mapped in multiples of the page size. -For a file that is not -a multiple of the page size, -the remaining bytes in the partial page at the end of the mapping -are zeroed when mapped, -and modifications to that region are not written out to the file. -The effect of -changing the size of the underlying file of a mapping on the pages that -correspond to added or removed regions of the file is unspecified. -.PP +.SH VERSIONS On some hardware architectures (e.g., i386), .B PROT_WRITE implies @@ -760,6 +726,57 @@ The relevant flags are: .BR MAP_POPULATE , and .BR MAP_STACK . +.SS C library/kernel differences +This page describes the interface provided by the glibc +.BR mmap () +wrapper function. +Originally, this function invoked a system call of the same name. +Since Linux 2.4, that system call has been superseded by +.BR mmap2 (2), +and nowadays +.\" Since around glibc 2.1/2.2, depending on the platform. +the glibc +.BR mmap () +wrapper function invokes +.BR mmap2 (2) +with a suitably adjusted value for +.IR offset . +.SH STANDARDS +POSIX.1-2008. +.SH HISTORY +POSIX.1-2001, SVr4, 4.4BSD. +.\" SVr4 documents additional error codes ENXIO and ENODEV. +.\" SUSv2 documents additional error codes EMFILE and EOVERFLOW. +.PP +On POSIX systems on which +.BR mmap (), +.BR msync (2), +and +.BR munmap () +are available, +.B _POSIX_MAPPED_FILES +is defined in \fI<unistd.h>\fP to a value greater than 0. +(See also +.BR sysconf (3).) +.\" POSIX.1-2001: It shall be defined to -1 or 0 or 200112L. +.\" -1: unavailable, 0: ask using sysconf(). +.\" glibc defines it to 1. +.SH NOTES +Memory mapped by +.BR mmap () +is preserved across +.BR fork (2), +with the same attributes. +.PP +A file is mapped in multiples of the page size. +For a file that is not +a multiple of the page size, +the remaining bytes in the partial page at the end of the mapping +are zeroed when mapped, +and modifications to that region are not written out to the file. +The effect of +changing the size of the underlying file of a mapping on the pages that +correspond to added or removed regions of the file is unspecified. .PP An application can determine which pages of a mapping are currently resident in the buffer/page cache using @@ -860,21 +877,6 @@ and .I length must both be a multiple of the underlying huge page size. .\" -.SS C library/kernel differences -This page describes the interface provided by the glibc -.BR mmap () -wrapper function. -Originally, this function invoked a system call of the same name. -Since Linux 2.4, that system call has been superseded by -.BR mmap2 (2), -and nowadays -.\" Since around glibc 2.1/2.2, depending on the platform. -the glibc -.BR mmap () -wrapper function invokes -.BR mmap2 (2) -with a suitably adjusted value for -.IR offset . .SH BUGS On Linux, there are no guarantees like those suggested above under .BR MAP_NORESERVE . |