Installing the out-of-band stage
Before you can direct the incoming interrupt flow to out-of-band handlers, you need to install the out-of-band interrupt stage. Conversely, you need to remove the out-of-band stage from the interrupt pipeline when you are done with receiving out-of-band events.
A symbolic name describing the high priority interrupt stage which is being installed. This information is merely used in kernel messages, so it should be short but descriptive enough. For instance, the EVL core installs the “EVL” stage.
This call enables the out-of-band stage context in the interrupt pipeline, which in turn allows an autonomous core to install out-of-band handlers for interrupts. It returns zero on success, or a negated error code if something went wrong:
-EBUSY The out-of-band stage is already enabled.
This call disables the out-of-band stage context in the interrupt pipeline. From that point, the interrupt flow is exclusively directed to the in-band stage.
This call does not perform any serialization with ongoing
interrupt handling on remote CPUs whatsoever. The autonomous core must
synchronize with remote CPUs before calling disable_oob_stage() to
prevent them from running out-of-band handlers while the out-of-band
stage is being dismantled. This is particularly important if these
handlers belong to a dynamically loaded module which might be unloaded
right after disable_oob_stage() returns. In that case, you certainly
don’t want the .text section containing interrupt handlers to vanish
while they are still running.
