Subject: Re: Supporting sector size != DEV_BSIZE -- patches
To: Bill Studenmund <wrstuden@netbsd.org>
From: Ignatios Souvatzis <is@netbsd.org>
List: tech-kern
Date: 06/03/2002 23:33:06
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On Mon, Jun 03, 2002 at 12:49:34PM -0700, Bill Studenmund wrote:
> On Sat, 1 Jun 2002, Trevin Beattie wrote:
>=20
> > I've implemented a fix for the ffs filesystem so that all upper-level d=
isk
> > operations use DEV_BSIZE blocks, and the actual sector size is left to =
the
> > physical device driver (below the buffer cache).  I've successfully
> > created, mounted, and written to a virtual disk using 2048-byte sectors.
> > Next thing I need to do is run the patched NetBSD on real hardware (I've
> > been using VMware for testing :-) and see if it will work with a SCSI MO
> > drive.
>=20
> I don't think that's the best direction to go. I think it would be better
> to do everything in terms of underlying disk blocks. Mainly since physical
> block size is a property of the drive

actually, of the medium - this is interesting for some drives with removable
media, like 90mm MO drives. With 640 MB media and up, the blocksize is 2048
bytes with 540MB, 230MB and 128MB, it is 512 bytes.

Of course, your argument:=20
> , so if you take a drive to another
> machine, it will work. If we depend on DEV_BSIZE (and I'm understanding
> you right), then different kernels will look in different places.

still applies.

Regards,
	Ignatios

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