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.
SEE ALSO
condvar(9),
mutex(9),
rwlock(9),
spl(9)