diff options
Diffstat (limited to 'cpu/task_switching/execution.txt')
| -rw-r--r-- | cpu/task_switching/execution.txt | 66 |
1 files changed, 66 insertions, 0 deletions
diff --git a/cpu/task_switching/execution.txt b/cpu/task_switching/execution.txt new file mode 100644 index 0000000..63a9126 --- /dev/null +++ b/cpu/task_switching/execution.txt @@ -0,0 +1,66 @@ +All task switches will occur after the current instructions in the queue have finished being processed and written + Will not conflict with other writes within the same instruction queue + Triggers <TODO> exception if multiple task switches occur within the same instruction queue + +TODO: mark current CPU executing it + +Call process: + Only allowed to be used by the original process + Triggers <TODO> exception otherwise + + Custom ID must match between the tdt at the index and the one specified by the instruction, and the target must be marked as valid + TODO: trigger exception? set a flag? + + One segment may be passed to the callee, used by the callee with all segment bits set + Caller may call with all segment bits set to not pass a segment + + Current process id in the tdt will be set to the id of the callee + Current segments will be saved to the tdt, and those of the callee will be loaded + PR as specified in the callee's tdt for the callable segment will be loaded, and current PR is saved to the tdt + IP of next instruction is saved to tdt + Stack pointers are saved to tdt + + Jumps to <callee's callable segment>, offset 0 + +Return process: + Only allowed to be used by the callee + Triggers <TODO> exception otherwise + + Segments will be loaded from the tdt + Process id in the tdt is set to the original process's id + Stack pointers are loaded from the tdt + PR is loaded from the tdt + + IP is loaded from the tdt + +Switch process: + Only allowed to be used by the original process + Triggers <TODO> exception otherwise + + Only allowed to switch to a process that is not currently active + TODO: trigger exception? set a flag? + + Custom ID must match between the tdt at the index and the one specified by the instruction, and the target must be marked as valid + TODO: trigger exception? set a flag? + + All registers are saved to the current tdt and loaded from the target's tdt index + + Loads all registers from the target's tdt index + +Switch process and exit exception/interrupt handler: + Only allowed to be used while in an exception/interrupt handler (TODO: different opcode for each?) + Triggers <TODO> exception otherwise + + Only allowed to switch to a process that is not currently active + TODO: trigger exception? set a flag? + + Only allowed to switch to a process that is valid + TODO: trigger exception? set a flag? + + All registers are saved to the current tdt and loaded from the target's tdt index + IP and PR are saved as if all exception/interrupt handlers returned + This saving step will be skipped if the entry for the current process is not flagged as valid + + Allows more interrupts to be processed + + Loads all registers from the target's tdt index |