Sharing I/O Memory

Wesley Miaw wesley at
Sat Jan 28 03:15:46 CET 2012

I have an L4 process requesting access to a large chunk (512MB) of
physical RAM using l4sigma0_map_iomem(). I am not using l4sigma0_map_mem()
because Fiasco is running in a different partition of physical RAM.

I would like to then grant full read/write access to the same memory to a
second L4 process, but I'm not sure how to do that. I believe from looking
at the sigma0 code that any memory, I/O or RAM, can only be allocated to
one L4 process at a time.

It also doesn't look like clans have anything to do with this, other than
the possibility of creating some shared memory for an IPC. But that's not
really what I want to do, I want both L4 processes to directly access the
memory. Is there some way to accomplish this?

Wesley Miaw
wesley at

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