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Re: Where to start...?

Maybe you should check out Joerg Brauns live-CD . It's available at, there are also two readme-files README.FIRST-i386live and README.i386live in the same directory.

Andy Ball wrote:

Hello Erik,

 EA> - A root device: if you don't have a hardrive you can use a
   >   memory disk embeded in the kernel (like in the installation-
   >   kernel) or NFS.

I'm keen to try the memory disk idea.  I plan to build a firewall soon
and would like it to have just a CD-ROM drive.  Some (which?) parts of
the filesystem need to be read/write.  If they're small enough, I can
have the rest mount read-only.

 EA> - Your own statically linked /sbin/init on the root device. This
   >   is the only userland process started by the kernel so if your
   >   system only need to run one program call it init and place it
   >   in /sbin. (Your program might have to do some of the things
   >   that the original init does, e.g. if your program wants do
   >   console io you will need a /dev/console and your init will
   >   have to open that device and dup2 fd's 0, 1 and 2 to that fd).

I think I get understand what you're saying, and where the application
is simple and space is at a premium I can see the sense in that
approach.  I'm not sure I'll try it just yet though ;-)

 EA> You can of course use the standard init and instead creat your
   > own /etc/rc.

That sounds like the direction I'll take.

 EA> If you want dynamically linked programs you will also need a
   > /usr/lib filled with the libraries your programs use (running
   > ldd on a binary will list does) and /usr/libexec/ld.elf_so is
   > also needed.

Hmm... can /usr/lib be read-only?

 EA> Some programs (like netstat) need to lookup data in the kernel
   > and for that they need the kernel symbol table. Normally the
   > symbol-table is read from /netbsd but if you use a memory disk
   > embeded in the kernel you might not want to put a kernel there


 EA> ...If that is the case you can use kvm_mkdb (8) to create a
   > /var/db/kvm.db that will be used instead.

I'll look that one up, I can see myself using it when I get to ROM or
Flash based systems.  For the machines with CD-ROM drives, could
/netbsd be a link to the kernel on the disc?

 EA> If you use existing programs you will of course need to lookup
   > what libraries they need (if dynamically linked), what config
   > files they use, other directories (e.g. they might want to put a
   > log file in /var/log) and if they exec other programs.

It sounds as though I have plenty of homework to do!  :-)

 EA> That's all I can think of for the moment.

Thanks a lot, you've given me enough to get started and that is

 - Andy Ball.

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