*BSD News Article 8477


Return to BSD News archive

Newsgroups: comp.unix.bsd
Path: sserve!manuel.anu.edu.au!munnari.oz.au!metro!ipso!runxtsa!bde
From: bde@runx.oz.au (Bruce Evans)
Subject: Re: At boot: file too big to load
Message-ID: <1992Dec3.074426.18271@runx.oz.au>
Organization: RUNX Un*x Timeshare.  Sydney, Australia.
References: <1992Nov22.225044.1344@ghost.dsi.unimi.it> <1992Nov23.070212.9393@tfs.com> <RAEBURN.92Dec1174219@tweedledumb.cygnus.com>
Date: Thu, 3 Dec 92 07:44:26 GMT
Lines: 15

>Doesn't the kernel bzero its own bss section on startup?

It does.

>Is there a reason the boot code has to take the bss into account?

Yes.  The bss has to fit below 640K because there is no RAM between
640K and 1MB.  Additionally, the GDT in the bootstrap code has to stay
alive after the kernel has cleared the bss.

I think that the checking has bugs.  The kernel clears a few pages
beyond the end of the bss (for page tables) and the bootstrap does not
allow for this.  So if the kernel is a little too big, it will crash.
-- 
Bruce Evans  (bde@runx.oz.au)