Dataspace juju

[Christian Prochaska]

Hi Daniel,

On 07/09/2013 09:36 PM, Daniel Waddington wrote:
> Hi,
> We're having bad juju with dataspaces.  As we try larger dataspaces
> things seem to go wrong (like hanging, bad mappings and exceptions).
>
> Can someone check out my test program..
> https://github.com/dwaddington/genode/blob/master/testing/src/core-api-1/main.cc
>
> and see what is going on?  Basically if you change the total memory use
> in the program (line 26) to something ~ > 512MB, then region conflicts
> happen.
>
> I tried this out this test on both fiasco.oc and nova with qemu and real
> PCs. Same result.  The NOVA run reports an "unresolvable exception" by
> pager:core-api-1.
>
> I could of course be doing something wrong with the APIs.
>
> Daniel

When using 'Rm_session::attach()', the Rm_session_component tries to
place the dataspace at an address which is aligned to the dataspace
size. So, when setting NUM_REGIONS to 8 or 16, your test works, but with
10 regions there will be small holes in the address space and the last
dataspace does not fit anywhere, causing a 'Region_conflict' exception.

Christian