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syscall.2: Minor tweaks 

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
This commit is contained in:
Michael Kerrisk 2015-12-30 11:33:56 +01:00
parent ddbe84e64e
commit 1078a69975
1 changed files with 25 additions and 12 deletions
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37
man2/syscall.2
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@ -188,21 +188,34 @@ Notes:
.RS 4
.IP [1] 4
On a few architectures,
a register is used as a boolean (0 == no error while -1 == error) to signal the
a register is used as a boolean
(0 indicating no error, and \-1 indicating an error) to signal that the
system call failed.
The actual error value is still contained in the return register.
On sparc, the carry bit (csr) in the processor status register (psr) is used
instead of a full register.
On sparc, the carry bit
.RI ( csr )
in the processor status register
.IR ( psr )
is used instead of a full register.
.IP [2]
NR is the system call number.
.I NR
is the system call number.
.IP [3]
For s390 and s390x, NR (the system call number)
may be passed directly with "svc NR" if it is less than 256.
For s390 and s390x,
.I NR
(the system call number) may be passed directly with
.I "svc\ NR"
if it is less than 256.
.IP [4]
On SuperH, the trap number controls the maximum number of args passed.
A trap #0x10 can be used with only 0 arg syscalls,
a trap #0x11 can be used with 0 or 1 arg syscalls,
and so on up to 0x17 for 7 arg syscalls.
On SuperH, the trap number controls the maximum number of arguments passed.
A
.IR "trap\ #0x10"
can be used with only 0-argument system calls, a
.IR "trap\ #0x11"
can be used with 0- or 1-argument system calls,
and so on up to
.IR "trap #0x17"
for 7-argument system calls.
.IP [5]
The x32 ABI uses the same instruction as the x86_64 ABI and is used on
the same processors.
@ -210,8 +223,8 @@ To differentiate between them, the bit mask
.I __X32_SYSCALL_BIT
is bitwise-ORed into the system call number for system calls
under the x32 ABI.
Both syscall tables are available though, so setting the bit is not a hard
requirement.
Both system call tables are available though,
so setting the bit is not a hard requirement.
.RE
.if t \{\
.in