[U-Boot] [PATCH] at91: board specific lowlevel_init.S

[Ilko Iliev]

Jean-Christophe PLAGNIOL-VILLARD wrote:
> On 16:01 Wed 22 Oct     , Ilko Iliev wrote:
>   
>> Jean-Christophe PLAGNIOL-VILLARD wrote:
>>     
>>> On 15:07 Wed 22 Oct     , Ilko Iliev wrote:
>>>   
>>>       
>>>> Jean-Christophe PLAGNIOL-VILLARD wrote:
>>>>     
>>>>         
>>>>> On 13:12 Wed 22 Oct     , Ilko Iliev wrote:
>>>>>   
>>>>>       
>>>>>           
>>>>>> Dear Mr. Denk,
>>>>>>
>>>>>>     
>>>>>>         
>>>>>>             
>>>>>>> Dear Ilko Iliev,
>>>>>>>
>>>>>>> In message <48FDFCA0.4090608 at ronetix.at> you wrote:
>>>>>>>         
>>>>>>>           
>>>>>>>               
>>>>>>>>> Maybe instead of adding mor #ifdef'ery here, we can turn
>>>>>>>>> lowlevel_init() into a "weak" function that can be redefined by board
>>>>>>>>> specific code?
>>>>>>>>>                 
>>>>>>>>>               
>>>>>>>>>                   
>>>>>>>> The lowlevel_init() is an assembler function called from another  
>>>>>>>> assembler function and the attribute .weak doesn't work.
>>>>>>>>             
>>>>>>>>             
>>>>>>>>                 
>>>>>>> What do you mean by "attribute .weak doesn't work" ?
>>>>>>>
>>>>>>>         
>>>>>>>           
>>>>>>>               
>>>>>>>> There are no assembler file in the U-BOOT tree which use weak functions.
>>>>>>>> Do you know how can I make an assembler function weak?
>>>>>>>>             
>>>>>>>>             
>>>>>>>>                 
>>>>>>> Well, if you don't know, then don't ask me, ask your compiler - he
>>>>>>> knows how to do this.
>>>>>>>
>>>>>>> For example, common/cmd_boot.c has this code snippet right at the
>>>>>>> beginning:
>>>>>>>
>>>>>>>  30
>>>>>>>  31 /* Allow ports to override the default behavior */
>>>>>>>  32 __attribute__((weak))
>>>>>>>  33 unsigned long do_go_exec (ulong (*entry)(int, char *[]), int argc, char *argv[])
>>>>>>>  34 {
>>>>>>>  35         return entry (argc, argv);
>>>>>>>  36 }
>>>>>>>
>>>>>>> Compile this with -S option, and you get this:
>>>>>>>
>>>>>>>  12 .Ltext0:
>>>>>>>  13         .align 2
>>>>>>>  14         .weak   do_go_exec
>>>>>>>  15         .type   do_go_exec, @function
>>>>>>>  16 do_go_exec:
>>>>>>>  17 .LFB87:
>>>>>>>  18         .file 1 "cmd_boot.c"
>>>>>>>  19         .loc 1 34 0
>>>>>>>  20 .LVL0:
>>>>>>>  21         mflr 0
>>>>>>>  22 .LCFI0:
>>>>>>>  23         stwu 1,-16(1)
>>>>>>> ...
>>>>>>>
>>>>>>>
>>>>>>> So to me it seems as if the attribute .weak is supposed to work just fine.
>>>>>>>
>>>>>>> What exactly is not working for you?
>>>>>>>
>>>>>>>         
>>>>>>>           
>>>>>>>               
>>>>>> With ".weak lowlevel_init" the function is marked as weak (I can see  
>>>>>> this in the ELF file) but it is not overwritten from the another  
>>>>>> lowlevel_init().
>>>>>>     
>>>>>>         
>>>>>>             
>>>>> try
>>>>>       
>>>>>           
>>>   
>>>       
>>>>>   
>>>>>       
>>>>>           
>>>> I tried and the result is:
>>>> lowlevel_init.S:32: Error: junk at end of line, first unrecognized  
>>>> character is `='
>>>>
>>>>     
>>>>         
>>> 	sorry try this
>>>
>>> 	.global __default_lowlevel_init
>>> 		.....
>>> 	.weak	lowlevel_init
>>> 	.set	lowlevel_init,__default_lowlevel_init
>>>
>>> 	after in the other asm
>>> 	.global lowlevel_init
>>> 		.......
>>>
>>> Best Regards,
>>> J.
>>>   
>>>       
>> Still doesn't work - the lowlevel_init is weak, but not overwritten.
>>
>> It works only if the second (strong) function is in the same archive.
>> Maybe this is a bug of the linker.
>>
>>     
> Do you specify that the 2 is type "func"
>   
The following variants don't work:

Variant A:
.globl lowlevel_init
.weak  lowlevel_init
.type  lowlevel_init,function
lowlevel_init:
   .......

Variant B:
.globl __default_lowlevel_init
.weak    lowlevel_init
.set    lowlevel_init,__default_lowlevel_init
.type   __default_lowlevel_init,function
lowlevel_init:
   .......


-- 
Mit freundlichen Grüßen/With best regards,
Ilko Iliev
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