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SubjectRe: [PATCH 2.6.23] ibmebus: Prevent bus_id collisions
Hi Joachim-

Joachim Fenkes wrote:
> Nathan Lynch <ntl@pobox.com> wrote on 29.08.2007 20:12:32:
> > Will anything break?
>
> Nope. Userspace programs should not depend on ibmebus' way of naming the
> devices; especially since some overly long loc_codes tended to be
> truncated and thus rendered useless. I have tested IBM's DLPAR tools
> against the changed kernel, and they didn't break.

Okay.


> > Also, I dislike this approach of duplicating the firmware device tree
> > path in sysfs.
>
> Why? Any specific reasons for your dislike?

struct device's bus_id field is but 20 bytes in size. Too close for
comfort?


> > Are GX/ibmebus devices guaranteed to be children of
> > the same node in the OF device tree? If so, their unit addresses will
> > be unique, and therefore suitable values for bus_id. I believe this
> > is what the powerpc vio bus code does.
>
> While there's no such guarantee (as in "officially signed document"), yes,
> I expect future GX devices to also appear beneath the OFDT root node. For
> the existing devices, the unit addresses are already part of the device
> name, so I save the need to use sprintf() again. Plus, I rather like using
> the full_name since it also contains a descriptive name as opposed to
> being just nondescript numbers, helping the layman (ie user) to make sense
> out of a dev_id.

Okay, but your layman isn't supposed to be relying on any
user-friendly properties of the name :) Hope he doesn't work on a
distro installer.

Anyway, if you're still confident in this approach, I relent. :)
-
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