Date: Mon, 15 Dec 97 13:46:28 -0400 From: "A. Ling" <aling@alum.mit.edu> To: "FreeBSD-questions" <freebsd-questions@FreeBSD.ORG> Subject: Advice/Experience with >2Gb IDE disks + early Phoenix 4.04 BIOS? Message-ID: <199712151847.NAA01697@havea.min.net>
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Now that I've had a few months of good experiences with 2.2.2R, I'd like to add a 4 Gb IDE disk for 2.2.5, but am concerned about a possible BIOS problem. FreeBSD will need to share the disk with OS/2 Warp Connect. If FreeBSD, once running, ignores the BIOS, then "not being able to use the full capacity" (see below) probably doesn't pertain, but I'm a bit worried that "crashing BIOS during bootup or upon detecting the drive" is a problem that happens before FreeBSD gets control of the machine. I suppose I can limit myself to a 2 Gb disk to avoid the problem, but I'm wondering before buying whether the list can suggest any other option, or other basis for enthusiasm for even trying a 4 Gb drive? My apologies in advance for a long post; I've tried to do my homework. The list archive says: ------------------excerpt: Date: Tue, 30 Jan 1996 14:03:31 -0700 (MST) From: Terry Lambert <terry@lambert.org> Subject: Re: questions related to getting freeBSD to boot from HD after > 1) Does freeBSD 2.1 support a translating BIOS or do I need to disable that? > I have three EIDE drives, (540 MB, 1.2 GB, 1.2 GB) and want to be able to FreeBSD itself doesn't use BIOS. It's a protected mode OS. FreeBSD's second stage boot use BIOS calls to read the kernel and then switched to protected mode to run it. You are limited to locating FreeBSD below BIOS cylinder 1024 (the boot track, disklabel, slice 'a', and replacement sectors, if BAD144 sector sparing is enabled), since the second stage boot must do BIOS-based I/O for all of these things. ---------------------end excerpt This sounds promising. On the other hand, an EIDE/ATA-2 FAQ at http://thef-nym.sci.kun.nl/cgi-pieterh/atazip/atafq-8.html#ss8.3 says: ------------------excerpt: 8.3 My 2GB+ drive is not recognized or crashes. Many BIOSes dated before 1996 contain bugs making them incompatible with drives of more than 4096 cylinders, which works out to be about 2GB in size. Some BIOSes have similar problems at the 8192 cylinder boundary (4GB). The effects may range from not being able to use the full capacity to a crashing BIOS during bootup or upon detecting the drive. ---------------------end excerpt At http://www.ptltd.com/techsupp/biosfaq.html#Q38 Phoenix somewhat encouragingly says: ------------------excerpt: Q38. How large a hard disk will my BIOS support? A38. The PC AT-type BIOS hard-disk interface supports a 528 MB or smaller hard disk under normal circumstances. Without conferring with the owner's manual or the computer manufacturer, there is no reliable method to predict how large a hard disk the BIOS will support. Phoenix helped create a new industry standard, called the Enhanced Disk Drive Support Specification (available in the technical library, this site), that supports hard disks up to 136.9 GB (gigabytes) in size as an optional feature. You must find out from your computer manufacturer if this feature was included in your BIOS. We do not know if the manufacturers to whom we have licensed the BIOS have installed this feature on your computer or not. Phoenix first offered this feature was to our customers in version 4.04 of the BIOS in early 1994. ---------------------end excerpt My other thoughts: Upgrading the motherboard BIOS appears not possible since the manufacturer (Zeos) is defunct. (I know about the Micron BBS, but I'm concerned an unsupported flash BIOS upgrade might not fix the problem, & might actually make something else break, and be irreversible at that.) Although the machine does have a SCSI controller with BIOS (Adaptec 1540 ISA), SCSI disks continue to seem beyond my budget. There's a PCI slot free for an add-on EIDE controller, but since I couldn't get an Adaptec 2940 to work there, I wonder whether an EIDE controller would -- evidently when I got the machine in 1995, the PCI standard was changing so rapidly that many compatibility problems subsequently became evident.
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