[lug] booting and kernel compiling (was dumpdates)

[Wayde Allen]

On Mon, 14 Aug 2000, John Starkey wrote:

> > You could probably think of it that way.  In Linux, the kernel, the file
> > system, and the collection of program is all called a distribution.  If
> > you are a purist only the kernel program itself is actually Linux.
> > Everthing else is someone's idea about what constitutes a good file
> > structure, and a collection of GNU/OpenSource software.
> 
> What exactly is needed for linux to boot then? Just the Kernel?

Hmmm ... that is a good question.  In a sense I guess it depends on what
you define as booting.  If the bios works, launches the boot loader, and
that in turn gets the kernel loaded I guess you could argue that the
system is booted even though there are no programs available to run.

You might want to check out my Linux Newbie articles at
<http://lug.boulder.co.us/docs.html>.  In particular check out
<http://lug.boulder.co.us/docs/newbie02.html>.

> I know I
> lost all my /bin like mv which is why I rebooted to floppy. My
> understanding, which is reinforced by this conversation, is that the
> Kernel calls individual, small, programs like mv when it needs it, or
> actually your call to mv makes the kernel search it out via $PATH.

You've kind of got this backward.  The kernel is really just a
standardized interface to the system hardware.  It doesn't have a reason
or desire to call the mv command.  That is where you come into the
picture.  You were the one who tried to invoke that command.  The path is
part of the shell environment that you interact with.

> So would it be safe to say that I can boot but if I don't have /bin it's
> just gonna sit there smil'in?

That is correct.

> /sbin is the kernel's equiv of /bin?

No, /sbin is where programs typically used by the system administrator
reside (See http://lug.boulder.co.us/docs/newbie05.html).

> I did do a make modules and gathered that that's what it does.

Yeah, it should create an object file for the modules in your source
distribution and update your /lib/modules, but that is all.

> I was actually referring to the image from bzdisk

OK, but my point is that a boot floppy simply kick starts the system,
mounts the root file system from your hard drive, and at that point is
basically done.  If the root file system has been modified from its
original form the boot floppy won't know what to do with it.  In other
words, it relies on the /bin directory for essentially all of its
programs.  A rescue floppy, install disk, or installation CD, on the other
hand doesn't (can't actually) make this assumption. 

> > I like your willingness to experiment!
> 
> Thanks, would you mind making the mistakes for me :}

Most of us have already made the mistakes.  The trick is for you to figure
out how best to make use of what we've learned.


- Wayde
  (wallen at boulder.nist.gov)