[Novalug] Linux boot, was Re: Kernel Compiles

James Ewing Cottrell 3rd JECottrell3@Comcast.NET
Sun Apr 18 11:11:36 EDT 2010


I dunno why nobody has mentioned this, but Process 0, at least on UNIX, 
was initially the (kernel mode) Swapper Process. Process 1 is, of 
course, (user mode) Init. BSD added (kernel mode) Process 2 as the 
Pageout Daemon.

Now GNU/Linux is Not UNIX, but many of the same patterns remain. Perhaps 
all those kernel threads are really just pieces of Process 0? That's 
just details.

But the kernel really *is* "just another program",  albeit a special 
one, and its main execution path ends up as a (more maybe "some") Process.

To its descendents, it is like your parents, or maybe the government, 
where you ask for things to be done.

Finally, to a Hypervisor, the kernel is "just another process", even if 
they call it a Domain.

JIM

Bryan J. Smith wrote:
> Parent Process ID (PPID).  Never tried a kill 0 myself, but feel free ...  ;)
> I know a kill 1 will, on virtually every POSIX platform, bring down the
> system (how gracefully varies ;).
> 
> 
> When process names are in brackets ([]), it means the arguments are not known.
> This is often because the kernel executes the process, instead of a command shell.
> 
> The kernel regularly forks or "wakes up" user processes to handle or monitor
> various operations when thresholds are reached.  E.g., pdflush is one such
> process when various virtual memory (vm) thresholds are crossed.
> 
> 
> 
> 
> ----- Original Message ----
> From: Ed James <edward.james@gmail.com>
> 
> This is where I get confused, because on my system init has PID 1 (and PPID 0).
> 
> Question (for nobody in particular):  for a "ps -ef", why are some of
> the process
> names in square brackets, like: [kthread] and [khelper]?  Seems like most (not
> all) were forked/spawned/execed/birthed by init.
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