SPLHI(10.2) SPLHI(10.2)
NAME
splhi, spllo, splx, islo - enable and disable interrupts
SYNOPSIS
int spllo(void)
int splhi(void)
void splx(int x)
int islo(void)DESCRIPTION
These primitives enable and disable maskable interrupts on the current
processor. Generally, device drivers should use ilock (see
lock(10.2)), sleep(10.2), or the functions in qio(10.2) to control
interaction between processes and interrupt handlers. Those routines
(but not these) provide correct synchronisation on multiprocessors.
Spllo enables interrupts and returns a flag representing the previous
interrupt enable state. It must not normally be called from interrupt
level.
Splhi disables all maskable interrupts and returns the previous inter‐
rupt enable state. The period during which interrupts are disabled had
best be short, or real-time applications will suffer.
Splx restores the interrupt enable state state to x, which must be a
value returned by a previous call to splhi or spllo.
Islo returns true (non-zero) if interrupts are currently enabled, and 0
otherwise.
SEE ALSO
lock(10.2), qio(10.2), sleep(10.2), intrenable(10.2)
SPLHI(10.2)
