Subject: Re: Thoughts about wedges
To: Bill Studenmund <>
From: Leo Weppelman <>
List: tech-kern
Date: 09/24/1999 21:00:58
On Thu, Sep 23, 1999 at 12:22:32PM -0700, Bill Studenmund wrote:
> On Thu, 23 Sep 1999, Leo Weppelman wrote:

[ ... ]
> >   * All disklabel related ioctl's will be moved out of the various drivers
> >     and will be either:
> >           - removed (ie. moved to the compat-area) [ is this sdcompat?? ]
> >           - moved to the wedge driver.
> It would be compat_14 if we depreciated the ioctl's.. but see below.

Sorry, I should have been clearer. With 'sdcompat' I meant the sdcompat
device from Charles' wedge proposal.

[ ... ]

> The idea is that the userland version would know how to read all of the
> partition types we know, and the kernel & boot blocks would know of a more
> limited set of types.

I like to point out that Wolfgang Solfrank had a good point on this a while
ago, in that it would probably be best to create one program per partition
type to read/write the partition info. The argumentation was that there are
quite a lot of scemes that all have there weird edges. Putting this in one
program would probably create a hard to maintain program. 
I _think_ the complexity problem most hits the creation/change of the labels.
The reading & interpretation is probably a lot simpler.

[ ... ]
> >   * It is a bit unclear when wedge info is destroyed. Must this be done
> >     explicitely (per disk device, per wedge)? Will media change be detected
> >     by the wedge driver?
> I'd say that the thread triggered when you first started talking about
> changing disklabels would cover when we want wedges to die. :-) I think
> the disklabel invalidation code would do the right thing here.

True. The trigger to mention it was the feed-back of the media change up
to the wedge driver.