Date: Mon, 18 Nov 1996 11:37:30 +1100 From: Bruce Evans <bde@zeta.org.au> To: dg@Root.COM, mark@quickweb.com Cc: bde@zeta.org.au, erich@uruk.org, hackers@FreeBSD.org Subject: Re: Memory probe(s) in FreeBSD Message-ID: <199611180037.LAA00343@godzilla.zeta.org.au>
next in thread | raw e-mail | index | archive | help
>> >Perhaps support >> >for all old boot blocks should be dropped. It is reasonable to require >> >that the (interface) version number of the bootblocks is >= that of the >> >kernel to reduce the number of cases. >> >> I strongly disagree with this, BTW. > >Just to agree with DG here, my computer has less base mem than the kernel >expects, and it isn't an old computer -> it's a dual PPro from digital. >Nevertheless, it's BIOS basemem is only 635K, which is < RTC basemem of >640K. If BSD didn't listen to the BIOS value from the bootloader, chances >are my system would be toast with fbsd... This is almost the opposite case to what David is disagreeing with. You're saying that you need new bootblocks. Very old bootblocks didn't supply the BIOS memory sizes. I doubt that you actually need them. -stable doesn't even implement using the BIOS basemem. >Not to mention the older 386 >and 486 machines I run -- who knows what old bootloader stuff these use! It continues to work. If you update the kernel, it is very easy to update the kernel at the same time (use disklabel -B). The requirement that new bootblocks works with old kernels ensure that the new bootblocks can boot the backup copy of the old kernel. If you forget to update the bootblocks, then it is easy to boot the old kernel using the old boot blocks to fix things up. Note that bootblock interface changes very rarely (in fact it hasn't changed, except for extensions, since it was introduced 2 years ago), but it is a good idea to keep them up to date anyway to pick up bug fixes (bootblocks more than a month old have serious bugs). Bruce
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?199611180037.LAA00343>