Re: [PATCH 13/13] ACPI: use unique number as bus_id of ACPI device in sysfs

[Zhang Rui <rui.zhang@intel.com>]

On Fri, 2006-11-24 at 01:36 -0500, Len Brown wrote:
> On Friday 24 November 2006 00:17, Len Brown wrote:
> > From: Zhang Rui <rui.zhang@intel.com>
> > 
> > Previously we used the device name in the DSDT, but would
> > crash upon encountering a duplicate.  Also, exposing
> > the DSDT device name to the user in a path isn't a
> > good idea, becauase it is arbitrary.
> > So just add two attributes for each device,
> > the full pathname in ACPI namespace and hardware_id.
> 
> While this addresses the potential name conflict of the previous version,
> I think this needs some work.
> 
> $ ls /sys/devices/0
> 1  10  2  3  4  5  57  6  7  8  9  bus  hid  path  power  subsystem  uevent
> 
> Assigning the unique numbers in a depth-first search
> leaves irritating gaps -- (see 10 and 57 above).
That's true.
But you know, ACPI namespace is a tree in nature. Depth-first is the
fastest way to traverse the ACPI namespace.
> Instance numbers need to be per-directory.
> 
instance numbers should be unique in the whole ACPI bus, as all of them
are linked to /sys/bus/acpi/devices/.
> Also, IMHO, the numbers by  themselves look a little strange,
> maybe dev0, dev1, dev%d etc. wouldn't look so strange?
> 
Yes, I can do that. :)
> Also, the ACPI spec has some pre-defined root name-spaces, and I think
> it makes sense to look up the device name against a small table of
> those reserved names and print something more interesting than
> a number.
> 
> eg. 
> _SB	system_bus
> _PR processors
> _TZ thermal_zones
> _SI system_indicators
> _GPE events
> 
Yeah. I can do that. But few devices can benefit from this. :(.


BTW: Maybe I can generate a patch to get the following result:
Five devices with the fixed name shown above if they are declared in the
BIOS
And add a prefix for every devices, the prefix is one of fixed names,
_SB _PR _TZ _SI _GPE. So devices are shown like _SB:dev001, _TZ:dev001,
_PR:dev033 etc.
But does this make sense? :(

The best way is to define a unique and meaning rule to name all the ACPI
devices. Unfortunately we haven't reached an agreement until now, but I
think we can leave this for further discussion.
> thanks,
> -Len