Hello,
I am working on a lock system using templates (based on what is found here:
https://github.com/seL4/camkes/tree/master/apps/mutex). This system can work,
but there are some issues with the components just going back and forth when
calling the locks. I believe this is an issue with multiple components using
the same endpoint to communicate with the "lock server" and the calls getting
pre-empted by other threads.
Here are the system calls that are used to hit the endpoint with the (un)lock
request.
seL4_Send(/*? ep ?*/, info);
info = seL4_Recv(/*? ep ?*/, NULL);
And in the lock server:
seL4_MessageInfo_t info = seL4_Recv(/*? ep ?*/, &sender);
...do locking things
seL4_Send(/*? ep ?*/, info);
So in order to prevent preempting by other threads, I went and changed the
(un)lock request system call to
info = seL4_Call(/*? ep ?*/, info);
Using print statements, I was able to determine that the lock server receives
the proper message on the endpoint and performs the locking operations.
However, when it reaches the seL4_Send operation, the system locks up. This
shouldn't be the case, because one component is waiting on the endpoint with
the seL4_Call, and the other is sending information on the same endpoint,
especially when having separate Send & Recv statements works.
Am I doing something incorrect?
Thanks for your help,
Chris Guikema
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