Re: [PATCH 2.6.23] ibmebus: Prevent bus_id collisions

Hi Joachim-

Joachim Fenkes wrote:

Nathan Lynch [off-list ref] wrote on 29.08.2007 20:12:32:

quoted

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.

quoted

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?

quoted

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.  :)