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

[York Sun]

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.

> 
> 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.

York