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Clarified the description of MREMAP_FIXED and restructured 

the text to reflect the fact that this flag is exposed
by glibc since version 2.4.
This commit is contained in:
Michael Kerrisk 2006-03-22 06:21:42 +00:00
parent b6c4058719
commit 8107e4b78d
1 changed files with 26 additions and 28 deletions
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54
man2/mremap.2
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@ -78,6 +78,28 @@ If the mapping is relocated,
then absolute pointers into the old mapping location
become invalid (offsets relative to the starting address of
the mapping should be employed).
.TP
.BR MREMAP_FIXED " (since Linux 2.3.31)"
This flag serves a similar purpose to the
.B MAP_FIXED
flag of
.BR mmap (2).
If this flag is specified, then
.BR mremap ()
accepts a fifth argument,
.IR "void *new_address" ,
which specifies a page-aligned address to which the mapping must
be moved.
Any previous mapping at the address range specified by
.I new_address
and
.I new_size
is unmapped.
If
.B MREMAP_FIXED
is specified, then
.BR MREMAP_MAYMOVE
must also be specified.
.PP
If the memory segment specified by
.I old_address
@ -141,37 +163,13 @@ The memory area cannot be expanded at the current virtual address, and the
flag is not set in \fIflags\fP.
Or, there is not enough (virtual) memory available.
.SH NOTES
Linux 2.3.31 added an additional
.I flags
value:
Prior to version 2.4, glibc did not expose the definition of
.BR MREMAP_FIXED ,
with a similar purpose to the
.B MAP_FIXED
flag for
.BR mmap (2).
If this flag is specified, then
and the prototype for
.BR mremap ()
accepts a fifth argument,
.IR new_address ,
which specifies a fixed address to which the mapping should be moved.
This address must be page aligned.
If
.B MREMAP_FIXED
is specified, then
.BR MREMAP_MAYMOVE
must also be specified.
Currently, neither the definition of
.B MREMAP_FIXED
nor a prototype for the
did not allow for the
.I new_address
argument are exposed by glibc.
.\" FIXME (Oct 05)
.\" But check http://sourceware.org/bugzilla/show_bug.cgi?id=1458
.\" to see whether glibc has been fixed to expose MREMAP_FIXED
.\" and the 'new_address' argument.
.\" According to the bug reply, on 14 Oct 05 Ulrich Drepper
.\" made the necessary changes in the glibc CVS.
.\" Changes aren't in glibc 2.3.6, perhaps 2.4?
argument.
.SH "CONFORMING TO"
This call is Linux-specific, and should not be used in programs
intended to be portable. 4.2BSD had a (never actually implemented)