[PATCH v3 2/8] [booke] Rename mapping based RELOCATABLE to DYNAMIC_MEMSTART for BookE

[Josh Boyer]

On Mon, Nov 28, 2011 at 5:59 PM, Scott Wood <scottwood at freescale.com> wrote:
> On 11/23/2011 10:47 AM, Josh Boyer wrote:
>> On Mon, Nov 14, 2011 at 12:41 AM, Suzuki K. Poulose <suzuki at in.ibm.com> wrote:
>>> The current implementation of CONFIG_RELOCATABLE in BookE is based
>>> on mapping the page aligned kernel load address to KERNELBASE. This
>>> approach however is not enough for platforms, where the TLB page size
>>> is large (e.g, 256M on 44x). So we are renaming the RELOCATABLE used
>>> currently in BookE to DYNAMIC_MEMSTART to reflect the actual method.
>
> Should reword the config help to make it clear what the alignment
> restriction is, or where to find the information for a particular
> platform.  Someone reading "page aligned" without any context that we're
> talking about special large pages is going to think 4K -- and on e500,
> many large page sizes are supported, so the required alignment is found
> in Linux init code rather than a CPU manual.
>
>>>
>>> The CONFIG_RELOCATABLE for PPC32(BookE) based on processing of the
>>> dynamic relocations will be introduced in the later in the patch series.
>>>
>>> This change would allow the use of the old method of RELOCATABLE for
>>> platforms which can afford to enforce the page alignment (platforms with
>>> smaller TLB size).
>>
>> I'm OK with the general direction, but this touches a lot of non-4xx
>> code.  I'd prefer it if Ben took this directly on whatever final
>> solution is done.
>>
>>> I haven tested this change only on 440x. I don't have an FSL BookE to verify
>>> the changes there.
>>>
>>> Scott,
>>> Could you please test this patch on FSL and let me know the results ?
>>
>> Scott, did you ever get around to testing this?  In my opinion, this
>> shouldn't go in without a Tested-by: from someone that tried it on an
>> FSL platform.
>
> Booted OK for me on e500v2 with RAM starting at 256M.
>
> Tested-by: Scott Wood <scottwood at freescale.com>
>
>> We add DYNAMIC_MEMSTART for 32-bit, and we have RELOCATABLE for
>> 64-bit.  Then throughout almost the rest of the patch, all we're doing
>> is duplicating what RELOCATABLE already did (e.g. if ! either thing).
>> It works, but it is kind of ugly.
>>
>> Instead, could we define a helper config variable that can be used in
>> place of that construct?  Something like:
>>
>> config NONSTATIC_KERNEL (or whatever)
>>     bool
>>     default n
>>
>> ...
>>
>> config DYNAMIC_MEMSTART
>>     <blah>
>>     select NONSTATIC_KERNEL
>>
>> ...
>>
>> config RELOCATABLE
>>     <blah>
>>     select NONSTATIC_KERNEL
>
> I agree.

Suzie do you think you could respin this patch with the suggested
changes and include Scott's Tested-by?  The rest of the series looks
fine and I'd like to get it included in my next branch.

josh