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syscall.2: Minor fix-ups to Changhee Han's patch 

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
This commit is contained in:
Michael Kerrisk 2013-04-01 08:24:53 +02:00
parent 638fd4bfda
commit 9525301640
1 changed files with 16 additions and 14 deletions
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30
man2/syscall.2
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@ -37,7 +37,7 @@
.\" 2002-03-20 Christoph Hellwig <hch@infradead.org> .\" 2002-03-20 Christoph Hellwig <hch@infradead.org>
.\" - adopted for Linux .\" - adopted for Linux
.\" .\"
.TH SYSCALL 2 2012-08-14 "Linux" "Linux Programmer's Manual" .TH SYSCALL 2 2013-04-01 "Linux" "Linux Programmer's Manual"
.SH NAME .SH NAME
syscall \- indirect system call syscall \- indirect system call
.SH SYNOPSIS .SH SYNOPSIS
@ -80,8 +80,11 @@ and an error code is stored in
first appeared in first appeared in
4BSD. 4BSD.
Each architecture ABI has its own requirements on how system call arguments are passed to the kernel. Each architecture ABI has its own requirements on how
For system calls that have a glibc wrapper (i.g., most system calls) glibc handles the details of copy arguments to the right registers in a manner suitable for the architecture. system call arguments are passed to the kernel.
For system calls that have a glibc wrapper (e.g., most system calls),
glibc handles the details of copyiing arguments to the right registers
in a manner suitable for the architecture.
However, when using However, when using
.BR syscall () .BR syscall ()
to make a system call, to make a system call,
@ -90,25 +93,24 @@ For example, on ARM architecture, a
.I "long long" .I "long long"
argument is considered to be 8-byte aligned and to be split into two 4-byte arguments. argument is considered to be 8-byte aligned and to be split into two 4-byte arguments.
For example, the
.BR readahead () .BR readahead ()
system call could be called like below in ARM architecture. system call would be invoked as follows on the ARM architecture:
syscall(__NR_readahead, fd,
.I 0
, (unsigned int)(
.I offset
>> 32), (unsigned int)(
.I offset
& 0xFFFFFFFF), count)
.in +4n
.nf
syscall(__NR_readahead, fd, 0, (unsigned int)(offset >> 32),
(unsigned int)(offset & 0xFFFFFFFF), count);
.fi
.in
.PP
.I offset .I offset
is 64 bit and should be 8-byte aligned. is 64 bit and should be 8-byte aligned.
Thus, a padding is inserted before Thus, a padding is inserted before
.I offset .I offset
and and
.I offset .I offset
is split into two 32 bit arguments. is split into two 32-bit arguments.
.SH EXAMPLE .SH EXAMPLE
.nf .nf
#define _GNU_SOURCE #define _GNU_SOURCE