[ros-dev] Kernel System Page Table

[Alex Ionescu]

Hi Hartmut & Mm Experts,

It seems that on ROS, every process has its own Page Table for the 
Kernel Area/System Table. This needs to be updated with MmUpdatePageDir 
all the time, and creates a bunch of annoyances in the Context Switching 
code too (for example, I can't check the trap frame for VM_MASK because 
at that time the Page Directory hasn't been changed yet. I could change 
it before but that would screw up the optimizations. Philip Susi and I 
have researched this and arrived to the common conclusion that every new 
Process's Page Table should share the same System Page Table. I'm not an 
expert so maybe I'm not explaining it properly, but the System Page 
Table shouldn't have to be "inserted/mapped" into every Process's Page 
Table, it should already be there, shared amongst all processes.
I hope that made sense...if not, maybe Philip can fix up my explenation.

Is it possible for any of the Mm guys to implement this properly?
Thanks a lot..

Best regards,
Alex Ionescu