NAME
spllower, splraise
— modify system interrupt
priority level
SYNOPSIS
#include
<machine/intr.h>
void
spllower(int
s);
int
splraise(int
s);
DESCRIPTION
These functions raise and lower the interrupt priority level on i386. They are used by machine-dependent kernel code to implement the machine-independent spl(9) interface.In a multi-CPU system, these functions change the interrupt priority level on the local CPU only. In general, device drivers should not make use of these functions.
The
spllower()
function sets the system priority level to the one encoded in
s, if s is lower than the
current level. Otherwise, it does not change the level. Use
splx()
instead of spllower(), except in extraordinary
circumstances.
The
splraise()
function sets the system priority level to the one encoded in
s, if s is greater than the
current level, and returns the previous level. Otherwise, it does not change
the level, and it returns the current level. Except in extraordinary
circumstances, do not use splraise(). Use one of the
priority-raising functions defined in
spl(9), instead.