Prior to this commit the kernel would always trigger a full reschedule
on setPriority. This change allows the kernel to attempt a direct
switch, avoiding invoking the scheduler.
Colloquially known as "invert-fastpath".
Update verification efforts on ARM for the following seL4 changes:
- scheduling decisions done in possibleSwitchTo are moved to the
scheduler
- possibleSwitchTo only checks whether the candidate is valid for a
fast switch, not its priority, accepting possible candidates
immmediately as a switch-to scheduler action
- the scheduler checks the candidate against the current thread and
against the bitmaps before making a decision
- attemptSwitchTo and switchIfRequiredTo are gone
- scheduler is now more complicated, and numerous proofs related to it
are rewritten from scratch
- fast path now checks ready queues via the scheduler bitmaps
- L2 scheduler bitmap order reversed for better cache locality
Many iterations between the kernel and verification teams were needed
to get this right.
In X64 update the following to match the C kernel:
- TCB size-bits (11).
- Endpoint size-bits (4).
- Guard bits (58).
- Message registers.
For all architectures, replace magic numbers with defined constants in
specifications, and as far as possible in proofs:
- tcb_bits in abstract spec.
- tcbBlockSizeBits, cteSizeBits, ntfnSizeBits, epSizeBits in Haskell
spec, Haskell and C refinement proofs.
Corey Lewis
Victor Phan
MiladKetabi
Edward Pierzchalski
Mitchell Buckley
Gerwin Klein
Thomas Sewell
Michael Sproul
Rafal Kolanski
Matthew Brecknell
Alejandro Gomez-Londono
Alejandro Gomez-Londono
Miki Tanaka