Every process now has an init process like it has a session, and each
session belong to an init. Orphaned processes are reparented to its init
process. All descendent processes are SIGKILL'd when an init process exits
and creating additional processes/threads fails.
Add setinit(2) for becoming the init process for your child processes and
add getinit(2) for locating your init process.
Add TIOCSCTTY force flag that releases a terminal from its current session
and makes it the controlling terminal for the current session. This ioctl
is essential to transferring the controlling terminal to a nested init,
which has its own session.
Add TIOCUCTTY that releases the terminal as the controlling terminal for
its current session.
Remove INIT_PID as it is replaced by getinit(2).
Preempted threads are now removed from the runnable list until every
other thread has been preempted or the system goes idle. This ensures
threads that roundtrip to other threads get a full chance to perform
their work cooperatively without being starved by CPU intensive threads
whenever they yield.
The futex and kutex implementations used the same linked list for waiting,
however the futex implementation used kutexs and the same thread could be in
the same list twice in the case of contention. This case corrupted the wait
lists and led to deadlocks and lost wakeups. This change fixes the problem
by having separate data structures for futexes and kutexes.
Mutexes contended by multiple threads could lead to lost wakeups since only
one contended thread was awoken and subsequent unlocks are unaware of the
unawakened contended threads. This change fixes the problem with a temporary
solution of waking all the contended threads until a better design is
implemented.
Additional details are tweaked to be more reliable and simpler.
The idle thread is now actually run when the system is idle because it
truly goes idle. The idle thread is made power efficient by using the hlt
instruction rather than a busy loop.
The new futex(2) system call is used to implement fast user-space mutexes,
condition variables, and semaphores. The same backend and design is used as
kutexes for truly sleeping kernel mutexes and condition variables.
The new exit_thread(2) flag EXIT_THREAD_FUTEX_WAKE wakes a futex.
Sleeping on clocks in the kernel now uses timers for true sleep.
The interrupt worker thread now truly sleeps when idle.
Kernel threads are now named.
This is a compatible ABI change.
I hereby relicense all my work on Sortix under the ISC license as below.
All Sortix contributions by other people are already under this license,
are not substantial enough to be copyrightable, or have been removed.
All imported code from other projects is compatible with this license.
All GPL licensed code from other projects had previously been removed.
Copyright 2011-2016 Jonas 'Sortie' Termansen and contributors.
Permission to use, copy, modify, and distribute this software for any
purpose with or without fee is hereby granted, provided that the above
copyright notice and this permission notice appear in all copies.
THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.