Q:
What is the difference between SendSoftwareInterrupt and
FWSendSoftwareInterrupt?
A:
A: SendSoftwareInterrupt in DriverServicesLib doesn't actually
do anything except immediately call the associated interrupt
handler.
FWSendSoftwareInterrupt depends on a patch to WaitNextEvent
for it's behavior. In general when you call FWSendSoftwareInterrupt,
the handler installed using FWCreateSoftwareInterrupt gets
run the next time WaitNextEvent is called. When you call
FWCreateSoftwareInterrupt one of the parameters is a TaskID.
FWSendSoftwareInterrupt tries to make sure that the TaskID
of the software interrupt matches the TaskID of the current
process according to the Process Manager. If you don't care
what the current process is when you get called (as would
likely be the case for a driver) pass in kInvalidID instead
of FWCurrentTaskID when you call FWCreateSoftwareInterrupt.
This way the software interrupt will get called the next
time WaitNextEvent gets called after you call FWSendSoftwareInterrupt.
[Feb 13 2002]
| 
