Date: Fri, 03 Oct 1997 12:35:09 -0600 From: "Justin T. Gibbs" <gibbs@plutotech.com> To: Andrew Reilly <reilly@zeta.org.au> Cc: gibbs@plutotech.com, freebsd-scsi@FreeBSD.org Subject: Re: New SCSI Framework Patches Available Message-ID: <199710031835.MAA04392@pluto.plutotech.com> In-Reply-To: Your message of "Fri, 03 Oct 1997 21:57:58 %2B1000." <199710031157.VAA02092@gurney.reilly.home>
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>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. 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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