Question on "mappings as cache"

Marcus Völp voelp at
Tue Dec 9 11:35:59 CET 2003

Stefan Götz wrote:

>5. RM sends non-propagating request and waits for reply
>6. DSM checks validity and translates request
>7. DSM replies to RM
In general the DSM should not be able to alter regions it is not 
managing, i.e. at least the receive window must be shrinked to the 
region, the fault occured in. On x86-Pistachio the hack of modifying BR0 
in the UTCB of the faulting thread might work. On architectures that 
place BR0 in Registers this is not possible, so the steps 6 and 7 are 
required anyway.

>8. RM replies to faulting thread
>9. fautling thread resumes execution
>With this protocol, the client does not have to trust the DSM. If the
>DSM does not reply (properly), the RM can fix up the faulting thread to
>e.g. execute something like a signal handler.


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