Christian Stueble stueble@amaunet.cs.uni-dortmund.de writes:
I think Fiasco/L4 uses memory mapped I/O, not separated I/O?
Memory-mapped I/O (that is, I/O via memory accesses in the virtual address space) and I/O via the separate 16-bit I/O address space (with in/out instructions; ``port I/O'') are completely separate from each other. It is not possible to map the port address space into the virtual memory, and that means it is not possible to replace port I/O with memory-mapped I/O. That's why, the kernel needs to support port I/O.
Michael
Am Fre, 22 Okt 1999 schrieben Sie:
Christian Stueble stueble@amaunet.cs.uni-dortmund.de writes:
I think Fiasco/L4 uses memory mapped I/O, not separated I/O?
Memory-mapped I/O (that is, I/O via memory accesses in the virtual address space) and I/O via the separate 16-bit I/O address space (with in/out instructions; ``port I/O'') are completely separate from each other. It is not possible to map the port address space into the virtual memory, and that means it is not possible to replace port I/O with memory-mapped I/O. That's why, the kernel needs to support port I/O.
Yes, but I thought an IBM PC uses sepatated I/O, but also maps them into the memory. (A Linux docu said, that new device drivers use memory mapped I/O.. ). Books about PCs describe separated I/O only, so I think this was wrong.
-Chris-
Michael
hohmuth@innocent.com, hohmuth@inf.tu-dresden.de http://home.pages.de/~hohmuth/
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