Date: Fri, 27 Oct 2000 13:45:08 -0700 (PDT) From: John Baldwin <jhb@FreeBSD.org> To: Matt Dillon <dillon@earth.backplane.com> Cc: freebsd-stable@FreeBSD.org, hackers@FreeBSD.org, Fred Clift <fclift@verio.net> Subject: Re: Really odd "BTX halted" problem booting FreeBSD on VALinux h Message-ID: <XFMail.001027134508.jhb@FreeBSD.org> In-Reply-To: <200010272024.e9RKOHL07526@earth.backplane.com>
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On 27-Oct-00 Matt Dillon wrote: >:I have a bunch boxes based on the L440GX+ intel motherboard that get >:confused by 'dangerously dedicated' labels. If you want real fun, dd >:boo0 from 3.4 onto the first block of any hard disk in your system and >:you will be unable to boot _any_ device in your system as the bios gets a >:wedgie somewhere before the bootloader gets invoked. PXE or other network >:boot still works and from there you can 'fix' the disk, or you can just >:yank it from the box too. >: >:At any rate, I've found a workaround in that if I put in valid partition >:info into the boot0 bootblock, the wedgie problem goes away. >: >:Am I confused about something? Perhaps I'm mistaken about how things work >:-- if so, enlighten me, please. >:-- >:Fred Clift - fclift@verio.net -- Remember: If brute > > I think that the days of the 'dangerously dedicated partition' are > numbered. It has obviously caused much more havoc then people have > realized. We don't have time to fix it for the current release, but I > took a good hard look at the code and as far as I can tell the only > reason we *have* a dangerously dedicated partition at all is because > the disklabel code is too cheap to create a real one - it is just copying > the skeleton fdisk data from boot0 verbatim and leaving it. Disklabel > could very easily create a real partition - in fact, I think with my > proposed patch for labeling slices all it needs to do is exec > 'fdisk -I disk' to do it, and then generate a virgin label for the slice. No, unfortunately we can't quite kill dedicated mode yet. There are still potential cases where the geometry the BIOS uses and the geometry that sysinstall uses are different, resulting in sysinstall writing a MBR that the BIOS won't handle properly (it won't find boot1 on the FreeBSD slice in the right place). DD mode works around this by sticking boot1 as the second sector on the disk whose geometry can't be screwed up. If you remove DD mode then the workaround in this case is for the user to enter the BIOS setup, write down the geometry the BIOS thinks the disk has, and then use the set geometry command in sysinstall's fdisk editor to set the geometry to the one the BIOS is using so that sysinstall writes out a MBR that the BIOS can properly use. As you can see, the issues involved with PC booting are revolting at best. -- John Baldwin <jhb@FreeBSD.org> -- http://www.FreeBSD.org/~jhb/ PGP Key: http://www.baldwin.cx/~john/pgpkey.asc "Power Users Use the Power to Serve!" - http://www.FreeBSD.org/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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