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Diffstat (limited to 'microkernel')
| -rw-r--r-- | microkernel/viengoos/projects.mdwn | 31 |
1 files changed, 31 insertions, 0 deletions
diff --git a/microkernel/viengoos/projects.mdwn b/microkernel/viengoos/projects.mdwn index e4599dc1..b29607e9 100644 --- a/microkernel/viengoos/projects.mdwn +++ b/microkernel/viengoos/projects.mdwn @@ -24,6 +24,37 @@ corresponding to a frame, which is keyed on its physical address. # Major +## Address Space Management + +In Viengoos, a process's address space is managed entirely in user +space by the process itself. This creates two interesting problems: +dealing with circular dependencies resulting from having to manage the +address space data structures and accessing and manipulating the +address space data structures. + +First, managing the address space requires resources, which in turn +may require address space (e.g., data structures require memory which +require address space, etc.). We currently break this circular +dependency by trying to keep enough resources in reserve that +allocating resources for managing the address space never requires +more resources than are minimally in the reserve. The reserve is +currently chosen in an ad-hoc fashion. It would be nice to determine +it more systematically. Moreover, it would be nice to reduce the +cases in which a reserve is required. This may be possible by +restructuring some of the code. + +Second, the address space data structures are protected using a single +lock. This not only means that only a single thread can be updating +the address space at a time, but that if a thread faults and the +address space is locked, then the process dead locks! It should be +possible to at least walk the address space using lock-free +techniques. This requires updating the address space construction +code such that all addresses remain valid during any given +manipulation. Second, to avoid the mentioned dead-lock problem, we +try to ensure that accessing the data structures will never result in +a fault. This means protecting the stack. An alternative approach is +to use undo buffers. + # Thesis ## Capability aware compiler |