Re: [PATCH v2 06/15] ARM: i.MX: scratch: add FDT support

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

Hi,

On 2/9/26 9:50 PM, Marco Felsch wrote:
> On 26-02-06, Ahmad Fatoum wrote:
>> How about:
>>
>> struct imx_scratch_space {
>>         union {
>>                 u8 __b[CONFIG_SCRATCH_SIZE];
>>                 struct {
>>                         u32 bootrom_log[128];
>>                         u32 reserved[128];
>>                         struct optee_header optee_hdr;
>>                         u8 fdt[] __aligned(8);
> 
> This would require, that the 'fdt' element is always the last element.
> We could add a comment, but it's rather fragile IMHO.

What's fragile about it? Next one after you, will not be able to add a
new member and that's a good thing. They should rework this instead of
piling extra CONFIG variables with board-specific offsets.

> 
>>                 };
>>         };
>> };
>> static_assert(sizeof(struct imx_scratch_space)
>>           - offsetof(struct imx_scratch_space, fdt)
>> 			<= PBL_OPTEE_DTB_MAX_SIZE);
> 
> This would introduce a very strict dependency for CONFIG_SCRATCH_SIZE to
> the not always visible PBL_OPTEE_DTB_MAX_SIZE. As you said:

Wrap the assert in an #ifdef then.

> 
>>>> In that case, this should go to security/Kconfig and be named something
>>>> like PBL_OPTEE_DTB_MAX_SIZE. There's no need to ask every user that
>>>> configures barebox about this.
> 
> Therefore I would like to use your name suggestion
> PBL_OPTEE_DTB_MAX_SIZE but keep it loose like RK does.
> 
>> The benefits I see:
>>   - Just one argument to tune (CONFIG_SCRATCH_SIZE) like we already use
>>     for Rockchip
> 
> Rockchip is using two Kconfig switch too (ARCH_ROCKCHIP_ATF_FDT_SIZE).

Oh, I see. I can send patches to switch this over to
PBL_OPTEE_DTB_MAX_SIZE then.

> 
>>   - We still have a dedicated option that can be kept in-sync with the
>>     exact option value in OP-TEE to find problems at compile-time
>>   - Only those who actually use OP-TEE will be asked about
>>     PBL_OPTEE_DTB_MAX_SIZE
> 
> Good points!
> 
>> Would this work for you?
> 
> Please see above.

Cheers,
Ahmad

> 
> Regards,
>   Marco
> 
> 
>>
>> Cheers,
>> Ahmad
>>
>>
>>>
>>> Regards,
>>>   Marco
>>>
>>>
>>>>
>>>>
>>>> Cheers,
>>>> Ahmad
>>>>
>>>> -- 
>>>> Pengutronix e.K.                  |                             |
>>>> Steuerwalder Str. 21              | http://www.pengutronix.de/  |
>>>> 31137 Hildesheim, Germany         | Phone: +49-5121-206917-0    |
>>>> Amtsgericht Hildesheim, HRA 2686  | Fax:   +49-5121-206917-5555 |
>>>>
>>>>
>>>
>>
>> -- 
>> Pengutronix e.K.                  |                             |
>> Steuerwalder Str. 21              | http://www.pengutronix.de/  |
>> 31137 Hildesheim, Germany         | Phone: +49-5121-206917-0    |
>> Amtsgericht Hildesheim, HRA 2686  | Fax:   +49-5121-206917-5555 |
>>
>>
> 

-- 
Pengutronix e.K.                  |                             |
Steuerwalder Str. 21              | http://www.pengutronix.de/  |
31137 Hildesheim, Germany         | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686  | Fax:   +49-5121-206917-5555 |