Subject: Re: partition bookkeeping
To: der Mouse <mouse@Rodents.Montreal.QC.CA>
From: Frank van der Linden <>
List: tech-kern
Date: 09/22/1999 10:29:02
On Tue, Sep 21, 1999 at 04:33:24PM -0400, der Mouse wrote:
> Yeah...but I still don't see any need for a "raw partition" with
> wedges.  Just access the underlying device directly rather than doing
> anything with the wedge partition devices.

Exactly, yes. Remember, with wedges you're not talking about
"disklabels" anymore, you're talking about some wedge-bookkeeping
structure for a disk, which should contain *no* knowledge itself
about what a "raw" device is. The basic "raw" device is the whole
disk. If you want to access partitions in a "raw" fashion, then you
just need to configure a wedge to contain the whole partition.

The knowledge of the underlying partitioning scheme (which is
strictly MD) would be in 1) an MD corner of the kernel which deals
with creating an initial wedge configuration in order to find the
root partition and 2) the wedgeconfig user program. The wedgeconfig
user program would ideally know about all partitioning schemes,
because it would enable you, for example (together with FFS 
byteswapping) mount a disk from another NetBSD architecture
without any problems. Or from any other system whose file systems
we support. The kernel doesn't need to know about it, you just
let the userspace code figure it out, calculate the boundaries,
and push them into wedges.

Now, what should be discussed (and has been) is a naming scheme
for device nodes. It's a good opportunity to get rid of
the mess that is wd/sd naming, 'c' or 'd' for the name of the
"raw" disk device, etc.

- Frank