RMGR-Extension to control I/O access

[Christian Stueble]

Hello,

I don´t 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 don´t know if a task is able to change the CPL
or the I/O permission bitmap of another task. 

Ciao,
Christian
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 Christian Stueble............stueble at ls6.cs.uni-dortmund.de
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