[U-Boot] [GENERIC_BOARD] env problems before relocation with ppc8360

[York Sun <yorksun@freescale.com>]

+Kim.

Valentin,

I haven't touched 83xx for a while. I remember I had to fix gd->flags when
converting some 85xx boards to use generic board. Please see these commits

701e640145474131161de53a407d95d0d2f77082
8bae330f5c6542638da7136f39bc9c13214592cc
15672c6dbd7e5a110773480ccfe47b98ba1dc6f8

York


On 10/01/2014 08:27 AM, Simon Glass wrote:
> +York
> 
> Hi Valentin,
> 
> On 30 September 2014 01:03, Valentin Longchamp
> <valentin.longchamp@keymile.com> wrote:
>> Hi Simon,
>>
>> I'm very glad you answered this, I was busy with other stuff these last weeks
>> but I had planed to pick this issue again this week.
>>
>> On 09/28/2014 06:27 AM, Simon Glass wrote:
>>> Hi,
>>>
>>> On 26 August 2014 09:17, Valentin Longchamp
>>> <valentin.longchamp@keymile.com> wrote:
>>>>
>>>> Hello,
>>>>
>>>> Here is the outcome of my debug session today:
>>>>
>>>> On 08/25/2014 05:42 PM, Valentin Longchamp wrote:
>>>>> Hello,
>>>>>
>>>>> I am currently porting all the Keymile boards to CONFIG_SYS_GENERIC_BOARD.
>>>>> On u-boot 2014.10-rc1 I have all of them working quite well (at least booting
>>>>> and showing no obvious problem), except for our boards using a MPC8360
>>>>> from Freescale (kmcoge5ne and kmeter1, both using km8360.h as config) that do
>>>>> not boot at all.
>>>>>
>>>>> I have found out that u-boot crashes as soon as a getenv function call happens
>>>>> before relocation. When I disable them, u-boot seems to work fine. I am
>>>>> currently trying to debug further, but it's not clear yet exactly what causes
>>>>> the crash.
>>>>
>>>> So the problem is that for an unknown reason, the gd->flags are not correct and
>>>> getenv actually calls hsearch_h to look for the desired env variable. This fails
>>>> before relocation (due to the small stack ?).
>>>>
>>>> If I replace the board_f getenv_ulong calls in board_f.c with my getenv_f_ulong
>>>> function that explicitely calls getenv_f the board boots up nicely.
>>>>
>>>> Now the question is, why are my gd->flags not correct/corrupted ? Has someone
>>>> already seen something similar ? I unfortunateley cannot access gd easily with
>>>> the BDI, since it is located in the INIT_RAM which is a data cache, for which I
>>>> have no LAW configured (could work on that).
>>>
>>> I just saw this. There is condition code at the start of
>>> board_init_f() in board_f.c that might exclude your board. So your
>>> global data might not be zeroed.
>>>
>>
>> That's not exactly the problem here, since defining
>> CONFIG_SYS_GENERIC_GLOBAL_DATA did not solve the problem. However it made me
>> look at the right place and I have noticed that gd->flags are set in the generic
>> board_inif_f() and were not in the previous powerpc specific board_init_f(). If
>> I comment out the gd->flags = boot_flags in the board_init_f() function, then
>> everything works well.
>>
>> Since board_init_f() is called from the assembly code (in my case
>> mpc83xx/start.S), I guess the ulong boot_flags argument ends up being a register
>> (if the arguments are passed in register ... which I am not sure of for
>> powerpc). Since prior to the bl board_init_f call in the start.S file, there is
>> a call another C function (cpu_init_f()), I guess the register passed as
>> argument has an undefined content ... that ends up in gd->flags.
>>
>> I think that the best way to fix this is to make sure from start.S that
>> boot_flags (so the register) has a defined (zeroed ?) content ? But how to make
>> sure which register it is and that this will not change, since the compiler
>> comes into play here ?
> 
> I don't have a lot of knowledge of this platform. On ARM we are moving
> to a model where the global data is set up before calling
> board_init_f() and then again before board_init_r(). ARM uses r9
> always which seems to work nicely.
> 
> I wonder if the same solution can be used here? I added York in case
> he has ideas.
> 
> Regards,
> Simon
>