Re: MSI interrupts - Instructions

Working on a simple OS I thought it might be useful to be able to poll for interrupts when interrupts are disabled. I think there may be times where it is acceptable to process certain kinds of interrupts even if they were disable. So, I added a poll-for-interrupt instruction to the architecture. Which just checks for interrupts and continues if there is not one. I have seen wait-for-interrupt instructions before, but not sure about polling.
I also added a two-up-level return from interrupt instruction. I have not seen this in other architectures, but I needed it at one point. Interrupt information is stored on an internal stack, and it is tricky (slow) to manipulate it for a two-up-level return. It is an eight level stack with two or three words of information per level. It was a bit much to copy it all in software, so I added the hardware return. But it is a lot of extra hardware for a very rare occurrence.
Finding this discussion on interrupts informative. I have only done a modicum of work on an OS; tried to get things working with spinlocks.