Subject: How DECstation boots with NetBSD kernel -- Re: diskless 5000/200
To: None <port-pmax@NetBSD.ORG>
From: Toru Nishimura <nisimura@is.aist-nara.ac.jp>
List: port-pmax
Date: 07/10/1998 10:43:03
In article <Pine.GSO.3.99.999.9807091126180.6934-100000@deceit.anim.dreamworks.com>
abs@anim.dreamworks.com wrote

> He meant (if Gregory doesn't mind me answering for him :), that
> the client can only use bootp or rarp/bootparams (actually I
> think in -current it can be configured to try both, but it will
> only end up using one or the other).

Let me clearify how NetBSD/pmax netboots.  The point is BOOTP dialogs
twice throughout boot sequence.

/// Step.1 ///   

	>> boot 3/tftp        (5/tftp on machine mainslot resides on #5) 

    BOOT ROM broadcasts a bootp request.

/// Step.2 ///

    Upon receipt of valid bootp reply, BOOT ROM starts TFTP downloading
    talking with TFTP server which ROM was notified.

/// Step.3 ///

    Kernel image is loaded and control is handed to kernel entry point,
    then standard kernel boot messages start to be displayed on console.

/// Step.4 ///

    NetBSD kernel tries to mount root filesystem after successful device
    probe.  In the case of networking boot, kernel has two options here;
    to send BOOTP request, or sunrpc style BOOTPARAM request, in order to
    determine where the root filesystem is.   Current implementation of
    NetBSD/pmax kernel does BOOTP here.

So, with DECstations there is no need to configure RARP/BOOTPARAMD
things at all (happiness...)

Tohru Nishimura
Nara Institute of Science and Technology