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