* by default, warning messages go to stderr
* if -A or -a is used, send warning messages to stdout instead.
The behaviour in 1.50 meant that
somevar=`sysctl -n machdep.booted_kernel 2>/dev/null`
could end up with $somevar="machdep.booted_kernel: the value is not available"
rather than the more useful $somevar="".
(This way, "sysctl -A | grep ..." is still useful.)
for forking the traditional UNIX init(8) and it does the Mach port naming
service. We need mach_init for the naming service, but unfortunately, it
will only act as such if its PID is 1. We introduce a sysctl
(emul.darwin.init_pid) to fool a given process into thinking its PID is 1.
That way we can get mach_init into behaving as the name server.
Typical use:
/sbin/sysctl -w emul.darwin.init_pid=$$ ; exec /emul/darwin/sbin/mach_init
These are of use to userland code which previously depended on the
hard-coded values of LABELSECTOR and LABELOFFSET to figure out the
location of the disklabel for a particular platform.
With the introduction of umbrella ports such as evbarm, evbmips, etc,
the location of the disklabel may vary between kernels for the same
MACHINE. This sysctl will allow userland programs to remain independent
of the particular flavour of MACHINE in such cases.
that can be used to block a process after fork(2) or exec(2) calls. The
new process is created in the SSTOP state and is never scheduled for running.
This feature is designed so that it is esay to attach the process using gdb
before it has done anything.
It works also with sproc, kthread_create, clone...
for FreeBSD project. Besides huge speed boost compared with socketpair-based
pipes, this implementation also uses pagable kernel memory instead of mbufs.
Significant differences to FreeBSD version:
* uses uvm_loan() facility for direct write
* async/SIGIO handling correct also for sync writer, async reader
* limits settable via sysctl, amountpipekva and nbigpipes available via sysctl
* pipes are unidirectional - this is enforced on file descriptor level
for now only, the code would be updated to take advantage of it
eventually
* uses lockmgr(9)-based locks instead of home brew variant
* scatter-gather write is handled correctly for direct write case, data
is transferred by PIPE_DIRECT_CHUNK bytes maximum, to avoid running out of kva
All FreeBSD/NetBSD specific code is within appropriate #ifdef, in preparation
to feed changes back to FreeBSD tree.
This pipe implementation is optional for now, add 'options NEW_PIPE'
to your kernel config to use it.
simonb