Subject: Re: [PATCH] powerpc: fix MAC address entries for 83xx, 85xx, and 86xx device trees

From: Timur Tabi <[email-masked]>
Date: Tue, 26 Jun 2007 10:22:01 -0500

Segher Boessenkool wrote:

> Yeah, that's fine.   I just meant the current kernel (before
> .25) could detect you are using a uboot that won't work after
> .25 anymore, and shout at the user.  Would save you some bug
> reports ;-)

I don't think that's possible.  I'm only updating the DTS files, not the kernel, because 
the kernel has already been updated.  Any 2.6.21 or later kernel will work with any U-Boot 
and any DTS.  The only time we're going to run into a problem is if someone updates the 
DTS but does *not* update U-Boot.  In this case, U-Boot won't find what it's looking for. 
  Some U-Boots will even panic in these cases.  Not only that, but older U-Boots don't 
even check the version number of the device tree they're parsing, and they'll just fail 
silently when they get a version they don't understand.  Unfortunately, I don't see how I 
can fix these problems.

>> In other words, the current U-Boot and Linux code is written to not 
>> care what the other one does.  I have no plans to remove the code in 
>> the kernel that looks for obsolete entries (I'm talking about function 
>> of_get_mac_address), because it's "safe".
> 
> Well you should remove the "address" thing, it is _not_ safe.

Checking for 'address' after finding no match on 'mac-address' and 'local-mac-address' is 
safe, because if that's the only property that has a valid MAC address, I want to use it. 
  As long as there are people out there using U-Boot 1.1.x, we'll need to keep that code 
around.

>> However, now that you mention it, I could update function 
>> of_get_mac_address() to display a warning if it only finds the 
>> 'address' property.
> 
> Yeah exactly.

Ok, I will submit a patch to do that.

-- 
Timur Tabi
Linux Kernel Developer @ Freescale