Hello,
I donŽt know very much about the i386-processor and Fiasco, therefore I would like to know if the following RMGR/Fiasco extensions are possible.
1) As default, no task has I/O port access. (CPL > IOPL or I/O permission bitmap pointer invalid)
2) A task asks via IPC the RMGR for I/O port access, e.g. port=0x80, length=4.
3) The RMGR checks, if port access can be granted. If yes, the RMGR decreases the tasks CPL and/or changes the tasks I/O permission bitmap.
==> Task is able to access port 0x80 - 0x83.
The main question: I donŽt know if a task is able to change the CPL or the I/O permission bitmap of another task.
Ciao, Christian
l4-hackers@os.inf.tu-dresden.de