Heads up: Linus plans to kill ARM defconfigs

[Eric Miao]

On Fri, Jun 4, 2010 at 9:16 AM, Ryan Mallon <ryan at bluewatersys.com> wrote:
> Marek Vasut wrote:
>> Dne Pá 4. června 2010 01:33:35 Ryan Mallon napsal(a):
>>> Nicolas Pitre wrote:
>>>> On Fri, 4 Jun 2010, Ryan Mallon wrote:
>>>>> Is it worth being a bit proactive and getting rid of some of them in
>>>>> advance? Things like spear3[012]0_defconfig are basically identically
>>>>> except for the board type. Combining all three of those would remove
>>>>> 1500 lines of code.
>>>> Please go ahead with a patch.
>>> Hmm, not as easy as I thought. The three boards cannot be built into a
>>> single kernel since the arch/arm/mach-spear3xx/spear3[012]0.c files all
>>> extern a bunch of structs which have naming conflicts.
>>>
>>> It does look possible to rewrite that code so that all three boards can
>>> be built into a single kernel. I can try and put together a patch, but I
>>> don't have any hardware to test with.
>>>
>>> The at91 is actually in a similar state, where only one of the
>>> at91sam9260, at91sam9g45, etc can be selected. Again, it should be
>>> possible to rework the code so that most of the different cpus can be
>>> built into a single kernel. I'm sure other mach's are in a simliar
>>> state. Fixing these where possible would allow us to have single
>>> defconfigs per mach directory and reduce code churn, which is what Linus
>>> is really complaining about.
>>
>> I just tested, PXA (mach-pxa) probably can be compiled into single kernel
>> supporting all the boards.
>
> Yes, IIRC Russell and Eric did a huge amount of work to get pxa into
> that state.
>
> ryan at okiwi:configs$ grep "ARCH_PXA=y" * | wc -l
> 25
>
> Can we remove/combine some of those?
>

Definitely. In the end of the day, I would like to see pxa_defconfig only.
But at the moment, I need every board maintainer to review their defconfig
and combine them as much as possible. E.g.

palmte_defconfig   palmtt_defconfig   palmz71_defconfig  palmz72_defconfig

I'd guess can simply combine into one. (Marek, feel free to do it)

I'd more like a step to step work instead of a brutely removal of all defconfig,
not sure if Linus is going to buy in.

For those sub-arch which cannot simply compile a single kernel for multiple
boards, s5p* as previously mentioned, I suggest not to introduce any new
defconfig until the problem is solved.

Also, we are now working on a single kernel for multiple sub-arch (at least
what Nicolas and I am doing now, and welcome to join us). It's tough (the
way to handle different phys_offset is only the tip of the iceberg) and seems
now more and more necessary. so hopefully by the end of the day, we may
possible end up with only very few defconfig.