Date: Thu, 16 Mar 1995 17:03:29 +1000 From: Bruce Evans <bde@zeta.org.au> To: phk@ref.tfs.com, terry@cs.weber.edu Cc: current@FreeBSD.org, rgrimes@gndrsh.aac.dev.com Subject: Re: newfs: sectors per cylinder (4096) disagrees with disk label (36) Message-ID: <199503160703.RAA19633@godzilla.zeta.org.au>
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>1) The device-driver may use a geometry(A) to access the disk. >2) The UFS may be created with a geometry(B) != geometry(A) >3) The device driver may need to read the geometry(A) from the disklabel, > because the BIOS lies and the drive is too dumb to answer the question. > The disklabel is the only place this can come from. Only on old devices that are currently unsupported because they also require bad144 support. Anyway, for sliced devices, geometry(A) is stored in the label for the whole disk and is not necessarily related to the geometries(B) stored in the BSD labeled slices on the disk. You can put a 4096 * 1 geometry in the slices is that is good for file systems. >I don't see any point in having the device-drivers even know about geometry, >considering that LFS for instance doesn't care a hoot, and I will strongly >work to get the ties already in place broken. The wd driver has to know for some old devices (those that don't allow their translation to be programmed, a subset of the currently unsupported devices). Bruce
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