posix_fadvise.2, pread.2, readahead.2, sync_file_range.2, truncate.2: Refer to syscall(2) for ABI semantics on certain 32-bit architectures

Also: in sync_file_range.2 and posix_fadvise.2 remove description
of conventional calling signature as flawed, and in
posix_fadvise.2, de-emphasize focus on ARM, and rather phrase
as a more general discussion of certain architectures.

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>

man2/posix_fadvise.2

@@ -25,7 +25,7 @@
 .\" 2005-04-08 mtk, noted kernel version and added BUGS
 .\" 2010-10-09, mtk, document arm_fadvise64_64()
 .\"
-.TH POSIX_FADVISE 2 2010-10-09 "Linux" "Linux Programmer's Manual"
+.TH POSIX_FADVISE 2 2013-04-01 "Linux" "Linux Programmer's Manual"
 .SH NAME
 posix_fadvise \- predeclare an access pattern for file data
 .SH SYNOPSIS
@@ -151,18 +151,25 @@ call
 or
 .BR fdatasync (2)
 first.
-.SS arm_fadvise()
+.SS Architecture-specific variants
-The ARM architecture
+Some architectures require
-needs 64-bit arguments to be aligned in a suitable pair of registers.
+64-bit arguments to be aligned in a suitable pair of registers (see
-On this architecture, the call signature of
+.BR syscall (2)
+for further detail).
+On such architectures, the call signature of
 .BR posix_fadvise ()
-is flawed, since it forces a register to be wasted as padding between the
+shown in the SYNOPSIS would force
+a register to be wasted as padding between the
 .I fd
 and
 .I len
 arguments.
-Therefore, since Linux 2.6.14, ARM defines a different
+Therefore, these architectures define a version of the
-system call that orders the arguments suitably:
+system call that orders the arguments suitably,
+but otherwise is otherwise exactly the same as
+.BR posix_fadvise ().
+
+For example, since Linux 2.6.14, ARM has the following system call:
 .PP
 .in +4n
 .nf
@@ -171,10 +178,11 @@ system call that orders the arguments suitably:
 .fi
 .in
 .PP
-The behavior of this system call is otherwise exactly the same as
+These architecture-specific details are generally
-.BR posix_fadvise ().
+hidden from applications by the glibc
-No library support is provided for this system call in glibc.
+.BR posix_fadvise ()
-.\" No ARM support in glibc.
+wrapper function,
+which invokes the appropriate architecture-specific system call.
 .SH BUGS
 In kernels before 2.6.6, if
 .I len

man2/pread.2

@@ -22,7 +22,7 @@
 .\" the source, must acknowledge the copyright and authors of this work.
 .\" %%%LICENSE_END
 .\"
-.TH PREAD 2 2012-04-30 "Linux" "Linux Programmer's Manual"
+.TH PREAD 2 2013-04-01 "Linux" "Linux Programmer's Manual"
 .SH NAME
 pread, pwrite \- read from or write to a file descriptor at a given offset
 .SH SYNOPSIS
@@ -130,6 +130,11 @@ The glibc
 and
 .BR pwrite ()
 wrapper functions transparently deal with the change.
+
+On some 32-bit architectures,
+the calling signature for these system calls differ,
+for the reasons described in
+.BR syscall (2).
 .SH BUGS
 POSIX requires that opening a file with the
 .BR O_APPEND

man2/readahead.2

@@ -25,7 +25,7 @@
 .\" 2004-05-40 Created by Michael Kerrisk <mtk.manpages@gmail.com>
 .\" 2004-10-05 aeb, minor correction
 .\"
-.TH READAHEAD 2 2010-09-10 "Linux" "Linux Programmer's Manual"
+.TH READAHEAD 2 2013-04-01 "Linux" "Linux Programmer's Manual"
 .SH NAME
 readahead \- perform file readahead into page cache
 .SH SYNOPSIS
@@ -89,6 +89,11 @@ The
 .BR readahead ()
 system call is Linux-specific, and its use should be avoided
 in portable applications.
+.SH NOTES
+On some 32-bit architectures,
+the calling signature for this system call differs,
+for the reasons described in
+.BR syscall (2).
 .SH SEE ALSO
 .BR lseek (2),
 .BR madvise (2),

man2/sync_file_range.2

@@ -27,7 +27,7 @@
 .\"     Andrew Morton's comments in fs/sync.c
 .\" 2010-10-09, mtk, Document sync_file_range2()
 .\"
-.TH SYNC_FILE_RANGE 2 2010-10-09 "Linux" "Linux Programmer's Manual"
+.TH SYNC_FILE_RANGE 2 2013-04-01 "Linux" "Linux Programmer's Manual"
 .SH NAME
 sync_file_range \- sync a file segment with disk
 .SH SYNOPSIS
@@ -186,11 +186,15 @@ need 64-bit arguments to be aligned in a suitable pair of registers.
 .\" See kernel commit edd5cd4a9424f22b0fa08bef5e299d41befd5622
 On such architectures, the call signature of
 .BR sync_file_range ()
-is flawed, since it forces a register to be wasted as padding between the
+shown in the SYNOPSIS would force
+a register to be wasted as padding between the
 .I fd
 and
 .I offset
 arguments.
+(See
+.BR syscall (2)
+for details.)
 Therefore, these architectures define a different
 system call that orders the arguments suitably:
 .PP

man2/truncate.2

@@ -40,7 +40,7 @@
 .\" Modified 2002-04-06 by Andries Brouwer <aeb@cwi.nl>
 .\" Modified 2004-06-23 by Michael Kerrisk <mtk.manpages@gmail.com>
 .\"
-.TH TRUNCATE 2 2011-09-08 "Linux" "Linux Programmer's Manual"
+.TH TRUNCATE 2 2013-04-01 "Linux" "Linux Programmer's Manual"
 .SH NAME
 truncate, ftruncate \- truncate a file to a specified length
 .SH SYNOPSIS
@@ -240,6 +240,11 @@ system calls that handle large files.
 However, these details can be ignored by applications using glibc, whose
 wrapper functions transparently employ the more recent system calls
 where they are available.
+
+On some 32-bit architectures,
+the calling signature for these system calls differ,
+for the reasons described in
+.BR syscall (2).
 .SH BUGS
 A header file bug in glibc 2.12 meant that the minimum value of
 .\" http://sourceware.org/bugzilla/show_bug.cgi?id=12037