type/status/etc inquiries. (PR kern/37915)
This is clearly a design problem in tty, but we need a cheap fix now.
The problem is that ttyinput() tries to pull a spinlock which
is already held on calls to t_oproc.
The workaround is based on the fact that within wscons code, the
wsdisplay_emulinput() function is only called directly from
wsdisplaystart(). So we can be sure that the tty lock is held,
and use an inofficial entry point in ttc.c which avoids the locking.
These ate certainly more assumptions than needed by the fix
proposed in the PR, but it doesn't affect (and slow down) other
tty drivers.
proclist_mutex and proclist_lock into a single adaptive mutex (proc_lock).
Implications:
- Inspecting process state requires thread context, so signals can no longer
be sent from a hardware interrupt handler. Signal activity must be
deferred to a soft interrupt or kthread.
- As the proc state locking is simplified, it's now safe to take exit()
and wait() out from under kernel_lock.
- The system spends less time at IPL_SCHED, and there is less lock activity.
usable VGA console ("call ddb_vgapost")
-allow to switch from/to screens occupied by an X server if the graphics
device is console and in polling mode (ie DDB)
This together allows to get a DDB session on a VGA console if the
system crashed while X11 was running.
As long as the protocol to tell X servers about virtual screen switches
is as primitive as it is, it is unsafe to restart an X session afterwards.
So this is basically for crash analysis.
- Add a lot of missing selinit() and seldestroy() calls.
- Merge selwakeup() and selnotify() calls into a single selnotify().
- Add an additional 'events' argument to selnotify() call. It will
indicate which event (POLL_IN, POLL_OUT, etc) happen. If unknown,
zero may be used.
Note: please pass appropriate value of 'events' where possible.
Proposed on: <tech-kern>
which are called somewhere in the middle of system suspend. Since the
X server accesses hardware directly it is outside our control whether
the devices it accesses are already/still suspended or not, so the only
way is to detach it before any device suspends and re-attach after
everything is awake again.
-For that, export a function ("wsdisplay_handlex" for now) which is
to be called from central suspend/resume code.
-The right way to handle the (normally impossible) case that the X
server is not detached on suspend is to return an error which should
abort the suspend process. pmf doesn't yet handle errors of device
suspend handlers, so as a temporary measure try to suspend anyway,
to get at least a text console.
-Improve error handling of X server attach/detach and maintain a flag
which tracks whether the X server is really active.
be using the "syncops" protocol) rather than doing a full switch
to virtual screen 1. The latter doesn't have the expected result if
the X server is running on screen 1, and is too much policy for inside
the kernel anyway.
Introduce a mutex+condvar to synchronize these operations, to replace
the spltty()/tsleep(). (for now only used by the new functions,
should be extended to the normal vt switching code)
system was before on resume. This is the second attempt and got more
complicated due to the async nature of VT_ACTIVE. After the initial
switch, check that we ended up on the first screen and if not, wait for
the switch to happen.
