[U-Boot] [RFC][PATCH] Generate CRC of structure of Global Data for standalone apps

[Albert ARIBAUD]

Le 04/09/2011 01:50, Graeme Russ a écrit :
> On 04/09/11 05:44, Wolfgang Denk wrote:
>> Dear Graeme Russ,
>>
>> In message<4E621E4E.8010703 at gmail.com>  you wrote:
>>>
>>> Back the original question that spawned this - asked several times and
>>> never answered - Does a modification to the Global Data structure trigger
>>> an increment of XF_VERSION?
>>
>> I don't think so.  But I have to admit that I never thoroughly
>> verifyed this either.  The standalone code itself is not suposed to
>> reference GD in any way; and the U-Boot routines that the standalone
>> call can call are runnign in the context of the current U-Boot, where
>> everything fits together.  So unless somebody misuses something, it
>> should all work out well.  At least, that's my theory.
>
> So perhaps this should be removed from exports.h:
>
> #if defined(CONFIG_X86)
> extern gd_t *global_data;
> #endif
>
> And document that standalone applications must not directly access the
> global data structure.
>
> The whole point of the patch was that it is critical that when a standalone
> application accesses global data, the version of the structure that it is
> accessing is exactly the same as the version being accessed by U-Boot.
> There are two ways of handling this:
>
> 1) Add an export function to access global data members by name (reporting
> an error if the member does not exist)
> 2) 'Sign' the structure of the global data (this patch)

Seems like the export function is what we should be aiming for, except 
that IMO the list of these functions should match a list of functional 
properties that U-Boot standalone applications need regardless to how 
these properties are computed, not a list of members that happen to 
exist in a structure at a given moment.

> Regards,
>
> Graeme

Amicalement,
-- 
Albert.