Path: utzoo!attcan!uunet!lll-winken!lll-tis!ames!ucsd!sdcsvax!ucsdhub!hp-sdd!hplabs!hpda!hpcupt1!hpcuhb!hpindda!vandys
From: vandys@hpindda.HP.COM (Andy Valencia)
Newsgroups: comp.os.minix
Subject: Re: Problems modifying the kernel - creates nonbootable system.
Message-ID: <3580011@hpindda.HP.COM>
Date: 11 May 88 15:51:28 GMT
References: <12189@shemp.CS.UCLA.EDU>
Organization: HP Technical Networks, Cupertino, Calif.
Lines: 24


	Just for completeness, you should have told us what version
you are working with.  I will give you some guesses, all more or less
obvious.

1. Kernel Size/Process Size
	MINIX has edge cases where things will not work as you approach
the 64K limit for various processes.  While writing your boot floppy
the build program will tell you the size of each member.  If these
are getting *near* 64K, then you could have hit one of the edge conditions.
There are various pieces of code which can be chopped out to try and
lower this--I always start with the Olivetti support! :->

2. sbrk() craziness
	Definitely not your problem, but in the same vein.  Giving large
numbers to sbrk() can mess things up, due to the signed arithmetic used.
As I recollect, the code says something like "if the break is higher than
the bottom of stack, fail".  Which is fine, unless you give break a number
which wraps it around into your text segment.  Now, although break is *much*
lower than the stack, you are in trouble.  This was discovered by my
housemate; I will ask him to post the actual results.

			Good luck, and happy hacking!
			Andy Valencia
			vandys%hpindda.UUCP@hplabs.hp.com