Paul Brook wrote:
Perhaps it would be even simpler to have two interrupts. One as you
describe -- a sync interrupt -- which could not be turned off, A second
for a service request which would be triggered by firmware on the board
or the DMA controller.
Then the issue of turning the sync interrupt off and on is moved to the
driver since the APIC Intel acronym == Advanced Programmable Interrupt
Controller) on the motherboard already has the hardware to turn off
(ignore) an interrupt.
On a typical PCI system each device only gets a single interrupt pin (a PCI
bus has 4, but each device is only supposed to use 1), and several devices
share an interrupt line.
Thus all interrupts should be maskable on the device, and probably combined
into a single output after masking.
I'm not a PCI expert. However, you are talking about the actual
physical implementation in PCI. If masking is required, this would be a
function in the PCI interface. However, IIUC, PCI devices are allowed
multiple interrupts -- each PCI device is allowed to use all 4
interrupts. If they share common physical interrupt lines, this is an
issue with the PCI interface hardware and driver.
--
JRT
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