Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!watmath!clyde!rutgers!im4u!ut-sally!ut-ngp!infotel!pollux!bobkat!m5d From: m5d@bobkat.UUCP Newsgroups: comp.os.minix Subject: Re: MINIX memory management (sort of) Message-ID: <534@bobkat.UUCP> Date: Tue, 3-Feb-87 18:10:31 EST Article-I.D.: bobkat.534 Posted: Tue Feb 3 18:10:31 1987 Date-Received: Wed, 4-Feb-87 07:23:12 EST References: <252@hqda-ai.UUCP> <1169@steinmetz.steinmetz.UUCP> <511@bobkat.UUCP> Reply-To: m5d@bobkat.UUCP (Mike McNally (dlsh)) Organization: Digital Lynx, Inc; Dallas, TX Lines: 41 Keywords: shared swapped jobs In article <511@bobkat.UUCP> m5d@bobkat.UUCP (Mike McNally (dlsh)) writes: >In article <1169@steinmetz.steinmetz.UUCP> davidsen@kbsvax.UUCP (william E Davidsen) writes: >> >>If you allocate a full 64k to data, there is hardware protection: you >>can't address more than that. ... > >What about a program with a bug in it? Like "strcpy(a, b)" when "a" is >not quite what I meant? It's real easy to make this kind of mistake; >how many times while debugging a program on a VAX (or whatever) do you >get SIGBUS or SIGSEGV? > >All it takes is a bad value passed to a routine which expects a >pointer. ... > > me Duhhhhh. Sorry. I just realized that the worst that can happen from a bad call to "strcpy" is that stuff beyond the logical end-of-segment (but within 64K of the base) could get trashed. If pointers are only 16 bits, it's hard to change the segment base value. Duhhhhh. Sorry William E. Davidsen. I just get carried away sometimes. AH! I could of course pass the address of a function to strcpy... Unlikely, but possible. I guess my point is that although it's not real easy to crash the system, it is possible, and the results are potentially bad (like a messed-up file system). But this is not my primary concern in life. If somebody wants to use this kind of a system, and they're happy, then so am I. Here's a more constructive question (which may have been answered, but I missed it if so). Does Minix provide a graphics interface to the screen of the PC? It would be nice if the "plot" routines worked. -- Mike McNally, mercifully employed at Digital Lynx --- Where Plano Road the Mighty Flood of Forest Lane doth meet, And Garland fair, whose perfumed air flows soft about my feet... uucp: {texsun,killer,infotel}!pollux!bobkat!m5d (214) 238-7474