Ali, here is trace that shows the problem:
---------------------------------------------------------------------------
5103756467000: system.cpu.interrupts: Got Trigger Interrupt message with
vector 0x30. // Here is the interrupt object receives the interrupt
5103756467000: system.cpu.interrupts: Interrupt is an LowestPriority.
.
.
.
5103756496000: system.cpu.interrupts: Generated regular interrupt (48)
fault object. // Interrupt object created for the CPU
.
.
.
5103791689000: system.pc.south_bridge.ide.disks0: Posting Interrupt // IDE
controller raises the interrupt line
5103791740000: system.cpu.interrupts: Got Trigger Interrupt message with
vector 0x3e. // Interrupt object receives the interrupt from the IDE
controller
5103791740000: system.cpu.interrupts: Interrupt is an LowestPriority.
.
.
.
5103791744000: system.cpu.interrupts: Interrupt 62 sent to core. // CPU
asks for interrupt information to be updated i.e. some interrupt is being
handled.
---------------------------------------------------------------------------
The problem lies in the o3 cpu itself. In the following piece code from
cpu/o3/cpu.cc file, the cpu can possibly update the interrupt info for a
different interrupt and invoke the interrupt handler for a different
interrupt. This is what happened above. The interrupt object thinks that
interrupt 62 is being handled, while the CPU actually handled interrupt
48. This results in IDE controller waiting for about 20 seconds, before it
switches from DMA to PIO mode and redoes all the work.
template <class Impl>
void
FullO3CPU<Impl>::processInterrupts(Fault interrupt)
{
// Check for interrupts here. For now can copy the code that
// exists within isa_fullsys_traits.hh. Also assume that thread 0
// is the one that handles the interrupts.
// @todo: Possibly consolidate the interrupt checking code.
// @todo: Allow other threads to handle interrupts.
assert(interrupt != NoFault);
this->interrupts->updateIntrInfo(this->threadContexts[0]);
DPRINTF(O3CPU, "Interrupt %s being handled\n", interrupt->name());
this->trap(interrupt, 0, NULL);
}
--
Nilay
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