Sharing I/O Memory

Wesley Miaw wesley at
Tue Jan 31 22:55:30 CET 2012


Everything seems to be working now that I've defined the RAM as a region
in the Io server's configuration file. After requesting access via
l4io_request_iomem_region() in both my tasks they can read/write the
memory. Thanks.

> Generally multiple tasks can have access to the same memory, be it RAM
> or device memory does not matter. Doing map/unmap operations for each
> request also sounds expensive to do. I think io is the one to look into,
> moe has no business with non-ram memory.

This confuses me. I thought part of sigma's job was to hand out memory as
needed, and only to do so to one task. I remember seeing something in the
sigma library code that checked who the owner of the memory was before
returning it. Otherwise what prevents one task from clobbering another
task? Or does that only apply to memory that is indirectly
requested/allocated like via new/malloc?

Wesley Miaw

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