[PATCH 2/5] arm: preserve ATAGS in /chosen/atags in the Device Tree

Jason Cooper jason at lakedaemon.net
Fri Jun 7 13:59:13 EDT 2013


On Fri, Jun 07, 2013 at 07:16:51PM +0200, Thomas Petazzoni wrote:
> Dear Jason Cooper,
> 
> On Fri, 7 Jun 2013 10:32:49 -0400, Jason Cooper wrote:
> 
> > > Well, I don't think what you say here is really fair. Before the DT was
> > > in place, unless I missed it, there was no standard way of letting the
> > > bootloader pass MAC addresses to the kernel. And Marvell's development
> > > on those Armada 370/XP platforms predates the introduction of the
> > > Device Tree in the Linux kernel (the code we have originally been give
> > > was a 2.6.3x), so it's really not their fault to not have a DT-capable
> > > bootloader at this point.
> > 
> > To be accurate, I think Nico is referring to the fact that Marvell
> > assigned their own ATAG without going through Russell.
> 
> Right, that's true.
> 
> > However, just like mach-types, are we assigning any new atags?  Can we
> > consider them deprecated?  If so, that changes the game.  Then what
> > Thomas is proposing is a "legacy compatibility" patch, as opposed to a
> > hole vendors can use to do their own thing.
> > 
> > We could add Arnd's suggestion of a time bomb on the common code in
> > atags_to_fdt.c to prevent mis-use.
> > 
> > I'm not 100% convinced of this, and I actually tend to agree with Nico
> > here, but I'd also like to find a workable solution.
> 
> I perfectly understand Nico and Russell concerns, for sure. But I'd
> also like to find a workable solution:
>  
>  * Passing the MAC address on the kernel command line is not something
>    that the network maintainer likes. See
>    http://lists.openwall.net/netdev/2011/11/17/82 and Dave Miller's
>    answer http://lists.openwall.net/netdev/2011/11/17/83.
> 
>  * Parsing the U-Boot environment is really not easy. How does the
>    kernel know where this environment is located? What if another
>    bootloader than U-Boot is used? Reading the U-Boot environment from
>    the kernel sounds clunky.

I agree on both points.  Let's see what Nico and Russell think of using
Arnd's suggestion of the time bomb, but used in atags_to_fdt.c.

thx,

Jason.



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