[U-Boot-Users] [PATCH] Update to stand alone program feature

[Jerry Van Baren]

Jeff Mann wrote:
>> Technically, you write: "function_no is defined by the enum  
>> type  of _exports.h, so it must be included in the stand 
>> alone program."
>>
>> I will reject this patch. As the name  "_exports.h"  suggests, 
>>  it  is intended to contain implementation internals that are 
>> not supposed to be used by application code.
> 
> Let me clearify (then I can update the doucmentation if we come up with
> a better description). As you know, the list of functions in _exports.h
> is used to create the enumerated type: XF_get_version 0, XF_getc 1,
> XF_tstc 2, ... Etc. So as long as the user has included exports.h or has
> uses some other means to identify the function's jump table inxex number
> in his/her stand along program, he can know if that function is
> available in u-boot. 
> 
> This is useful when, for exmaple, a company builds boards both with and
> without NAND support. A stand along program will be able to know that
> that board was loaded with a u-boot that did not incude NAND support. 

[snip]

> -JM

What would be Really Cool[tm] would be to enhance the elf loading 
capability to resolve unresolved link addresses for the standalone 
application entry points.  Then the standalone program could be loaded 
by u-boot with the interfaces fixed up by the elf loader.  This would 
eliminate all the problems of jump tables and keeping them synchronized.

<http://www.gnu.org/software/binutils/manual/html_chapter/binutils_14.html>
<http://www.linuxjournal.com/article/1059>
<http://www.linuxjournal.com/article/1060>

Possible problems that come to mind...
* Code bloat
* The coupling between GPL u-boot and potentially proprietary standalone
     programs arguably is tighter.  In practical terms, I don't see this
     as an issue, but it really isn't my call.  I would contend this is
     similar to linux loadable device drivers and the current standalone
     programs have license to call back into u-boot - the same functions,
     simply a different interface mechanism.
* My ignorance may be making a molehill out of a mountain of work
* So many interesting things to do, so little time :-(

Best regards,
gvb