ref: 9429dd64f746ebf9afc634f50f3f88d9408cfa7e
dir: /sys/man/9/kproc/
.TH KPROC 9 .SH NAME kproc, pexit, postnote \- kernel process creation, termination and interruption .SH SYNOPSIS .ta \w'\fLvoid 'u .B void kproc(char *name, void (*func)(void*), void *arg) .PP .B void pexit(char *note, int freemem) .PP .B int postnote(Proc *p, int dolock, char *n, int flag) .SH DESCRIPTION .I Kproc creates a new kernel process to run the function .IR func , which is invoked as .BR "(*func)(arg)" . The string .I name is copied into the .B text field of the .B Proc structure of the new process; this value is the name of the kproc in the output of .IR ps (1). The process is made runnable; it will run when selected by the scheduler .IR sched (9). The process is created with base and current priorities set to .BR PriKproc . It shares the kernel process group and thus name space. .PP A kernel process terminates only when it calls .IR 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 .IR postnote . .I Note is a null string on normal termination, or the cause of If .I freemem is non-zero, any memory allocated by the process is discarded; it should normally be non-zero for any process created by .IR kproc . Use the following to terminate a kernel process normally: .IP .EX pexit("", 1); .EE .PP .I Postnote sends a software interrupt to process .IR p , causing it, if necessary, to wake from .IR sleep (9) or break out of a .IR rendezvous (2) or an .IR eqlock (9), with an .IR error (9) `interrupted'. Up to .B NNOTE notes can be pending at once (currently 5); if more than that arrive, the process is forced out of .IR sleep , .I rendezvous and .IR eqlock , but the message itself is discarded. .I Postnote returns non-zero iff the note has been delivered successfully. If .I dolock is non-zero, .I postnote synchronises delivery of the note with the debugger and other operations of .IR proc (3). .I Flag is zero, or one of the following .TP .B NDebug Print the note message on the user's standard error. Furthermore, suspend the process in a .B Broken state, preserving its memory, for later debugging. .TP .B NExit Deliver the note quietly. .TP .B NUser The note comes from another process, not the system. .PP The kernel uses .I postnote to signal processes that commit grave faults, and to implement the note and kill functions of .IR proc (3). A device driver should use .I postnote only to tell a service process, previously started by the driver using .I kproc , that it should stop; the note will cause that process to raise an .IR error (9). For example, a process started to read packets from a network device could be stopped as follows when the interface is unbound: .IP .EX postnote(readp, 1, "unbind", 0); .EE .PP where .I readp points to the appropriate .BR Proc . The text of the message is typically irrelevant. .SH SOURCE .B /sys/src/9/port/proc.c