Subject: [PATCH] ARM: nommu: re-enable use of vexpress without ARCH_MULTIPLATFORM

From: [email-masked] (Rob Herring)
Date: Wed, 09 Jan 2013 21:51:54 -0600

On 01/09/2013 02:48 PM, Russell King - ARM Linux wrote:
> On Wed, Jan 09, 2013 at 02:39:36PM -0600, Rob Herring wrote:
>> On 01/09/2013 02:22 PM, Arnd Bergmann wrote:
>>> On Wednesday 09 January 2013, Nicolas Pitre wrote:
>>>> On Wed, 9 Jan 2013, Arnd Bergmann wrote:
>>>>
>>>>> On a related topic, I still think we should fix ARCH_MULTI_V7 not
>>>>> to select ARCH_VEXPRESS unconditionally and come up with a better
>>>>> way to avoid having an empty platform list to make 'allnoconfig'
>>>>> still work.
>>>>
>>>> The virtual guest platform support that Will and Marc did is small 
>>>> enough that it could always be selected in place of vexpress.
>>>
>>> But that only helps when ARMv7 is selected, unless we want to build
>>> it only for ARMv4, v5 or v6 kernels.
>>>
>>> Besides, the only reason we can't have a kernel without any platform
>>> selected is that the linker script has code in it to intentionally
>>> barf on that because it's guaranteed not to boot on any hardware.
>>>
>>> If we decide that building an allnoconfig without any platform
>>> is actually ok, we could just as well rip out that error statement.
>>>
>>
>> That patch is already posted, but Russell doesn't like it as you can
>> have a kernel that doesn't boot. You don't like the allno and randconfig
>> failures, so we're stuck. I think there are dozens of config options
>> that will make you not boot on any given platform, so failing to boot
>> because you did not select your machine is a non-issue.
> 
> What I actually suggested is that we should be aiming for the DT side
> of things to get to the point where DT is just another _single_ platform
> as far as that code goes, and that DT should describe the hardware
> sufficiently well that we don't have multiple machine_desc things to
> select via DT - so a DT kernel would have exactly one machine_desc (or
> maybe even zero! - with the linker script check conditional on !CONFIG_OF)
> 
> That then gets rid of the issue entirely.

I agree completely. I look at mach-highbank (and mach-virt) as what else
needs to be done in terms of refactoring or moving to DT. That's
certainly a long term goal, but what is the short term solution?

Rob