diff options
| -rw-r--r-- | man2/getpagesize.2 | 56 | ||||
| -rw-r--r-- | man2/syscalls.2 | 4 |
2 files changed, 20 insertions, 40 deletions
diff --git a/man2/getpagesize.2 b/man2/getpagesize.2 index b82586f36..7abc3a246 100644 --- a/man2/getpagesize.2 +++ b/man2/getpagesize.2 @@ -37,6 +37,19 @@ returns the number of bytes in a memory page, where "page" is a fixed-length block, the unit for memory allocation and file mapping performed by .BR mmap (2). +.SH VERSIONS +A user program should not hard-code a page size, +neither as a literal nor using the +.B PAGE_SIZE +macro, +because some architectures support multiple page sizes. +.P +This manual page is in section 2 because +Alpha, SPARC, and SPARC64 +all have a Linux system call +.BR getpagesize () +though other architectures do not, +and use the ELF auxiliary vector instead. .SH STANDARDS None. .SH HISTORY @@ -44,46 +57,11 @@ This call first appeared in 4.2BSD. SVr4, 4.4BSD, SUSv2. In SUSv2 the .BR getpagesize () -call is labeled LEGACY, and in POSIX.1-2001 -it has been dropped; -HP-UX does not have this call. -.SH NOTES -Portable applications should employ -.I sysconf(_SC_PAGESIZE) -instead of -.BR getpagesize (): -.P -.in +4n -.EX -#include <unistd.h> -long sz = sysconf(_SC_PAGESIZE); -.EE -.in +call was labeled LEGACY, +and it was removed in POSIX.1-2001. .P -(Most systems allow the synonym -.B _SC_PAGE_SIZE -for -.BR _SC_PAGESIZE .) -.P -Whether -.BR getpagesize () -is present as a Linux system call depends on the architecture. -If it is, it returns the kernel symbol -.BR PAGE_SIZE , -whose value depends on the architecture and machine model. -Generally, one uses binaries that are dependent on the architecture but not -on the machine model, in order to have a single binary -distribution per architecture. -This means that a user program -should not find -.B PAGE_SIZE -at compile time from a header file, -but use an actual system call, at least for those architectures -(like sun4) where this dependency exists. -Here glibc 2.0 fails because its -.BR getpagesize () -returns a statically derived value, and does not use a system call. -Things are OK in glibc 2.1. +glibc 2.0 returned a constant +even on architectures with mutliple page sizes. .SH SEE ALSO .BR mmap (2), .BR sysconf (3) diff --git a/man2/syscalls.2 b/man2/syscalls.2 index 6c2313506..69f24ef29 100644 --- a/man2/syscalls.2 +++ b/man2/syscalls.2 @@ -324,7 +324,9 @@ T} \fBgetpeername\fP(2) 2.0 T{ See notes on \fBsocketcall\fP(2) T} -\fBgetpagesize\fP(2) 2.0 Not on x86 +\fBgetpagesize\fP(2) 2.0 T{ +Alpha, SPARC/SPARC64 only +T} \fBgetpgid\fP(2) 1.0 \fBgetpgrp\fP(2) 1.0 \fBgetpid\fP(2) 1.0 |