Date: Fri, 03 Oct 1997 14:23:11 -0700 From: Julian Elischer <julian@whistle.com> To: "Justin T. Gibbs" <gibbs@plutotech.com> Cc: Andrew Reilly <reilly@zeta.org.au>, freebsd-scsi@FreeBSD.ORG Subject: Re: New SCSI Framework Patches Available Message-ID: <3435623F.500F9F30@whistle.com> References: <199710031835.MAA04392@pluto.plutotech.com>
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Justin T. Gibbs wrote: > > >On 2 Oct, Justin T. Gibbs wrote: > >> Supported peripherals: > >> > >> Direct Access driver (da): > >> 512 byte sectored disk drivers. Support for other sector sizes is > >> planned, but further investigation on the "right" approach for this > >> is needed. It probably belongs in the disk-slice code. > > > >Pardon for the unhelpful intrusion, but could someone please explain > >the issue here? > > The issue is that most of the system deals with devices in "DEV_BSIZE" > chunks (512bytes). In the past, each device driver has had to perform some > amount of conversion if the device block size doesn't match that value. > Performing the conversion to block sizes that are a power of 2 isn't hard, > but in some cases, the block size is an "odd" value (Try writing audio > tracks to a WORM for instance). I'd like to deal with this issue cleanly > and not require each and every device driver to handle this case on it's > own. Justin, I have new disk handling code that does this all cleanly. I'll send you a copy as soon as I get the last killer bugs out of it. in th emean-while don't spend too much time on this roblem as I'm working on it.. It will fit into your stuff just fine I think. > > So, the question is how to best handle the problem? NetBSD has a few PRs > in their gnats database that offer possible solutions. I just haven't had > time to really consider the problem in detail and come up with a clean > approach. > > >-- > >Andrew > > > >"The steady state of disks is full." > > -- Ken Thompson > > -- > Justin T. Gibbs > =========================================== > FreeBSD: Turning PCs into workstations > ===========================================
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