[U-Boot] [Patch v2 1/2] common/board_f: Preserve global data for mpc85xx and mpc86xx

[York Sun]

On 04/30/2014 04:52 PM, Scott Wood wrote:
> On Wed, 2014-04-30 at 16:48 -0700, York Sun wrote:
>> On 04/30/2014 04:44 PM, Scott Wood wrote:
>>> On Wed, 2014-04-30 at 16:40 -0700, York Sun wrote:
>>>> On 04/30/2014 03:57 PM, Scott Wood wrote:
>>>>> On Wed, 2014-04-30 at 15:56 -0700, York Sun wrote:
>>>>>> On 04/30/2014 03:51 PM, Scott Wood wrote:
>>>>>>> On Wed, 2014-04-30 at 15:48 -0700, York Sun wrote:
>>>>>>>> On 04/30/2014 03:45 PM, Scott Wood wrote:
>>>>>>>>> On Wed, 2014-04-30 at 14:31 -0700, York Sun wrote:
>>>>>>>>>> For powerpc SoCs (including mpc85xx, mpc86xx), global data is used for
>>>>>>>>>> initializing LAWs, before calling function baord_inti_f(). This data
>>>>>>>>>> should not be cleared later.
>>>>>>>>>>
>>>>>>>>>> Signed-off-by: York Sun <yorksun at freescale.com>
>>>>>>>>>> ---
>>>>>>>>>> Change log
>>>>>>>>>>  v2: Instead of adding back gd init for all PPC, preserve gd for mpc85xx and mpc86xx.
>>>>>>>>>>
>>>>>>>>>>  Note, need other maintainers to fix 83xx, 5xxx, 512x as I don't have boards to verify.
>>>>>>>>>>
>>>>>>>>>>  common/board_f.c |    6 +++++-
>>>>>>>>>>  1 file changed, 5 insertions(+), 1 deletion(-)
>>>>>>>>>>
>>>>>>>>>> diff --git a/common/board_f.c b/common/board_f.c
>>>>>>>>>> index cbdf06f..eebb377 100644
>>>>>>>>>> --- a/common/board_f.c
>>>>>>>>>> +++ b/common/board_f.c
>>>>>>>>>> @@ -970,7 +970,11 @@ static init_fnc_t init_sequence_f[] = {
>>>>>>>>>>  
>>>>>>>>>>  void board_init_f(ulong boot_flags)
>>>>>>>>>>  {
>>>>>>>>>> -#ifndef CONFIG_X86
>>>>>>>>>> +	/*
>>>>>>>>>> +	 * For MPC85xx, global data is initialized in cpu_init_early_f() and
>>>>>>>>>> +	 * used for init_law(). gd should not be cleared in this function.
>>>>>>>>>> +	 */
>>>>>>>>>> +#if !defined(CONFIG_X86) && !defined(CONFIG_MPC85xx) && !defined(CONFIG_MPC86xx)
>>>>>>>>>>  	gd_t data;
>>>>>>>>>>
>>>>>>>>>>  	gd = &data;
>>>>>>>>>
>>>>>>>>> It would be better to introduce a CONFIG_SYS_EARLY_GD (or similar)
>>>>>>>>> rather than growing a list here.
>>>>>>>>
>>>>>>>> That's do-able.
>>>>>>>>
>>>>>>>>>
>>>>>>>>> Is there any reason why the set of targets for which zero_global_data()
>>>>>>>>> is skipped is different from the set of targets where the gd
>>>>>>>>> instantiation and assignment is skipped?
>>>>>>>>
>>>>>>>> I would think the list should be identical. But without proper testing, I am
>>>>>>>> reluctant to copy the list. As you have suggested, start from 85xx first.
>>>>>>>> Non-mpc85xx can be dealt with when they get converted.
>>>>>>>
>>>>>>> None of those other PPC targets currently use the generic board.  They
>>>>>>> will be tested when they are converted.
>>>>>>>
>>>>>>
>>>>>> Are you suggesting to copy the list, instead of only putting those tested?
>>>>>
>>>>> I'm saying to use CONFIG_SYS_EARLY_GD for both things.
>>>>>
>>>>>>  It may save other maintainer some effort of debugging. But I can't be
>>>>>> sure they will all work.
>>>>>
>>>>> What good reason could there be for wanting to skip clearing of a gd
>>>>> that was just allocated on the stack?
>>>>>
>>>>
>>>> Relocating is OK. But clearing is not. At least the used LAWs variable is
>>>> needed. There may be other variables as well. All data in gd is copied to new
>>>> location.
>>>
>>> Where do you get relocating from (at this stage of boot -- of course it
>>> will get relocated when U-Boot gets relocated)?  Either gd was
>>> initialized early, in which case we want to keep using it and not clear
>>> it, or it wasn't, in which case we want to allocate gd on the stack and
>>> clear it.
>>
>> Exactly. gd is used before board_init_f() for many cases.
> 
> Yes, that's the whole point of CONFIG_SYS_EARLY_GD.  What I'm saying is
> to forget about the current ifdef list around zero_global_data(), and
> replace it with CONFIG_SYS_EARLY_GD, which for now would only contain
> mpc85xx, mpc86xx, and x86.  Other targets can skip the zeroing if and
> when they also skip the stack allocation and assignment.

I can agree on this.

> 
>>> BTW, I see x86 also skips "gd = new_gd" in board_init_r(), so I wonder
>>> what is going on with gd on x86, and whether it makes sense to lump it
>>> in with CONFIG_SYS_EARLY_GD.
>>>
>>
>> Maybe x86 maintainers can chime in? If we define such macro, it should probably
>> sit right above board_init_f() so it can be seen easily. There is no other place
>> it is needed, yet.
> 
> I was thinking it would be set the same way other CONFIG symbols are
> set.
> 

That will be in include/common.h for cross-platform macros.

York