KPROC(10.2) KPROC(10.2)
NAME
kproc, setpri, swiproc, pexit - kernel process creation,
priority change, interrupt and termination
SYNOPSIS
void kproc(char *name, void (*func)(void*), void *arg, int
flags);
int setpri(int pri);
void swiproc(Proc *p, int interp);
void pexit(char*, int);
DESCRIPTION
Kproc creates a new Inferno kernel process to run the func-
tion func, which is invoked as (*func)(arg). The string
name is copied into the text field of the Proc structure of
the new process; although the value is not visible to Limbo
applications, it can appear in system messages written to
the console. The process is made runnable; it will run when
selected by the scheduler.
The new process always acquires the following attributes
from the creating process:
owner (Inferno user name)
host user and group IDs (in emu only)
floating-point attributes
Several resources can be shared with the creating process on
request, as determined by flags, which is the logical OR of
a subset of the following:
KPDUPPG If set, the new process shares the caller's pro-
cess group, which includes its process group ID
(for killgrp), name space (mounts, root and cur-
rent directory), and PIN for /dev/pin (see
cons(3)).
KPDUPFDG If set, the new process shares the caller's file
descriptor group; otherwise, it has no file
descriptor group, and (if it intends to open
files) must call newfgrp(10.2) to obtain an empty
file descriptor group.
KPDUPENVG If set, the new process shares the caller's envi-
ronment group (currently applies in emu only).
KPDUP Equivalent to all of the above.
If a particular option is not set, the new process will have
a nil reference for the corresponding resource.
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KPROC(10.2) KPROC(10.2)
Setpri sets the priority of the calling process to pri and
returns its previous priority level. If a (now) higher pri-
ority process is ready to run, the system will reschedule.
The available priority levels are shown below, arranged from
highest to lowest priority, with examples of the type of
processes intended to use them:
PriLock The highest priority, used by lock(10.2) for
a process entering a critical section
PriRealtime Intended for processes supporting applica-
tions with real-time constraints, such as
video telephony.
PriHicodec MPEG codec
PriLocodec Audio codec
PriHi Any task with keen time constraints.
PriNormal The priority of most processes in the system.
PriLo
PriBackground
Swiproc sends a software interrupt to process p, causing it
to wake from sleep(10.2) with an error(10.2) `interrupted'.
Unless interp is non-zero (ie, the Dis interpreter is the
caller), the process is also marked `killed'.
An Inferno process terminates only when it calls pexit,
thereby terminating itself. There is no mechanism for one
process to force the termination of another, although it can
send a software interrupt using swiproc. The arguments to
pexit are ignored in Inferno, but are included for compati-
bility with kernel components of Plan 9; use
pexit("", 0);
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