Re: SCSI disk devices

Matthias Urlichs (
9 May 1997 11:00:26 +0200

Martin von Loewis <> writes:

> The remaining question is how to divide the 64 bits between major and minor
> number. Linus claims this is not an issue. I don't agree, because file

The kernel still has to dispatch to the driver based on the major number.

Anyway, I'd use 16 bits major and 48 bits minor. That's enough space for
drivers and enough bits for all SCSI buses you're ever going to find on a
system (let's see, 8 adapters with 4 channels with 16 devices with 8 LUNs (oops,
more for SCSI-3?) with 32 partitions is about 20 bits, so we have spare room for
all the flag bits of the SCSI tape driver _and_ an additional 16-bit number
to play with). Of course, 32/32 has the advantage that you don't need
64-bit integers to represent a minor number, and it still seems to be large

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