On Tue Aug 19, 2014 at 20:59:16 -0700, Noah Zentzis wrote:
On 08/17/2014 12:55 AM, Adam Lackorzynski wrote:
So now I'm not sure how you want to proceed. Are your programs special ones, i.e. that they are quite different from L4 programs or are they L4 programs? I wondering where to do the paging, however, in any case it sounds to me like doing it in a different task would be good.
To address your question: You map the pager to the task with the dst_task->map() call as shown above. The pager is probably a thread you implement, for doing your work. The order does not really matter because the thread only starts running until the run_thread call, i.e. it does not matter whether the pager cap (any cap) is mapped before or after it has been registered with the thread.
How would I configure the new task to use the same pager that the current task is? Looking at libloader, I'd think it would be something like:
task-map(L4Re::This_task, env->rm().fpage(), env->rm().snd_base());
but I'm not sure if I need to create a new region map or something like that. I think I've got memory mapping working, but the process dies with an unhandled read page fault.
Yes, you'd need to create a new region mapper for the new task, one that knows about the virtual address space layout of that one. Should be possible by using a new instance of Region_map as done in the l4re_kernel. You'll also need to create an IPC-gate to be used as the pager for the new task and which is routed to the Region_map instance for that task. You also need to handle other events that come through the pager channel, see Dispatcher::dispatch in l4re_kernel/server/src/dispatcher.cc for the switch block.
Adam