Date: Mon, 10 Aug 2009 12:54:03 -0600 (MDT) From: Warner Losh <imp@bsdimp.com> To: des@des.no Cc: jhs@berklix.com, freebsd-hardware@freebsd.org, mav@freebsd.org, freebsd-arch@freebsd.org Subject: Re: Do we still need ATA disk CHS addressing? Message-ID: <20090810.125403.74653324.imp@bsdimp.com> In-Reply-To: <86eirjbjl3.fsf@ds4.des.no> References: <200908101640.n7AGeYH0054650@fire.js.berklix.net> <86eirjbjl3.fsf@ds4.des.no>
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From: Dag-Erling Sm=F8rgrav <des@des.no> Subject: Re: Do we still need ATA disk CHS addressing? Date: Mon, 10 Aug 2009 20:38:16 +0200 > "Julian H. Stacey" <jhs@berklix.com> writes: > > Alexander Motin <mav@FreeBSD.org> writes: > > > Have anybody seen ATA drive without LBA support in last years? > > Yes > = > Have you really, or did you just assume that "old" means "no LBA"? > = > > I run 20+ assorted hosts from 4.11 to 7.2 Uni & Dual proc, i386 (re= al 386!) > > to 686 & amd64 so I guess I'm = > > A) Pretty vulnerable to legacy scare. > > B) A litmus tesst for a wider community of others, some with old= er kit, = > > not on lists or with bleeding edge latest hardware, but will = > > get hit when stuff eg HCS gets declared legacy=3Ddumped. > = > Do you seriously intend to run FreeBSD 9 on kit that is too old to > support LBA? We're talking early nineties here. CHS doesn't scale p= ast > 504 MB, so any ATA disk larger than that must peforce support LBA. I= > bought my first 1 GB drive (Connor CFP1080) in 1995. Is that also true in the pc98 realm? There's a number of weird combinations there which use CHS addressing, but that's kinda forced onto it by weird pc98 disk label format. I don't know if this is required, and older stuff just won't work or not, but I do know that there be dragons there. I know, at the very least, that the system requires that the CHS geometry reported by the drive be faithfully preserved. It is something we should ask nyan-san about at the very least... As for the 'are you seriously going to run FreeBSD 9 on them' argument, there's a rather large number of systems that people said would be too slow to run FreeBSD 7 or 8, yet they are running them better than anticipated. They said that about many of the same systems that Julian is running today. My question, and maybe I missed this earlier in the thread, is what's the benefit to removing this support? How much code is saved? Having said all that, I think it is OK, but I'd definitely poll the pc98 guys first... Just to make sure they don't need it and re-fork the ata driver to get it :) Warner
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