[9fans] Looking for namespace details

[9fans] Looking for namespace details

[Glenn McGuire]

Hi,
	I'm trying to understand how namespaces are implemented in Plan9, and
I've run into a block.  I started tracing stuff like 'bind' and 'open'
through the source code, and they all point to
/sys/src/libc/9syscall/<blah>.s

All of these (dynamically generated) assembly functions appear to cause
a jump to a dispatch table.  ("INT 64, vec"-- a newbie guess would say
that we're jumping from user space to kernel space?)

My question is -- where is the code for the kernel side of these calls?
	-gm

Re: [9fans] Looking for namespace details

[Dan Cross]

You are correct about what they're doing.  The code is in
/sys/src/9/port and /sys/src/9/pc (or whatever architecture
you're using).

	- Dan C.

Re: [9fans] Looking for namespace details

[Russ Cox]

directly, /sys/src/9/port/sysfile.c.
but the code you care about (for name
spaces) is in /sys/src/9/port/chan.c
with a little in /sys/src/9/port/pgrp.c.

russ

Re: [9fans] Looking for namespace details

[rob pike, esq.]

> My question is -- where is the code for the kernel side of these calls?

Some of the system calls are wrapped in libc first - for example,
read() is a wrapper for pread() - but on average, system call foo is
connected by a trap through a table defined in
/sys/src/9/port/systab.h (generated automatically from
/sys/src/libc/9syscall/sys.h) to a routine in /sys/src/9/port/sys*.c
called sysfoo().  A few later system calls appear in files not
beginning with "sys", a regrettable lapse.

-rob

Re: [9fans] Looking for namespace details

[Fco.J.Ballesteros]

Try also with http://plan9.escet.urjc.es/who/nemo/9.ps.gz

It describes how the kernel works, including namespaces (although
for an old version of the kernel).

Re: [9fans] Looking for namespace details

[Glenn McGuire]

Thanks all.
I didn't expect such speedy replies on a saturday!
	-gm

Re: [9fans] Looking for namespace details

[David Presotto]

in /sys/src/9/port	- chan.c (the actual namespace), sysfile.c (the system calls for
changing the namespace)