Re: [Xen-devel] Re: Question on "xen-blkfront: handle Xen major numbers other than XENVBD"

[Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>]

Stefan Bader writes ("Re: [Xen-devel] Re: Question on "xen-blkfront: handle Xen 
major   numbers other than XENVBD""):
> Yeah, I understand the problem now that I thought of the possibility
> of having both name types in the configuration. Though I could
> imagine that in reality there will be no one having that done as it
> would have caused problems...  As you say, the only way to avoid any
> clashed is to have seperate namespaces.  But that again is
> unexpected now and people would complain.  The 4 letters offset
> probably still can get busted if someone decides to use hde and sda.

Nowadays people supply hd* because they're using HVM (and thus the
clashes happen with PV-on-HVM).  hde doesn't work for HVM because
there are only two two-channel ide controllers emulated in qemu-dm.

So I don't think this is an important configuration.

> Detecting clashes at allocation time and then using another name for
> the duplicate is likely to result in a random of the two to be the
> secondary.  My feeling would be that trying to map two namespaces
> into one will always be confusing and/or failing to some degree. The
> reason to go back would only be that this was broken before, so it
> can probably be expected that people have avoided that mix. So it
> would be as it has been before. But I bet there are other people
> that thought of it as a bug... Not an easy decision at all.

I think at this stage the best thing to do would be to leave Linux 3.x
as it is rather than changing things again.

Ian.

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