Re: [ECOS] eCos compile problem with arm-none-eabi- toolchain 2008q1

["simon.kallweit@intefo.ch" <simon.kallweit@intefo.ch>]

Xie Chun-B19413 wrote:
> Hi Simon,
> 	We use arm-none-eabi- toolchain 2008q1 release compile eCos. The
> compiler option -mcpu=cortex-a8 was used.
> 	And we met a strange problem. The compiler/linker couldn't
> calculate the right offset of the string pointer of function
> diag_printf. 
> 	
> 	For example,
> 	
> 	//some code
> 	diag_printf("string_1");
> 	diag_printf("string_2");
> 	//some other diag_printf was called
>
> 	diag_printf("string n");			//this function
> string pointer will not point to it's "string_n", but it will return to
> somewhere of "sting_1"
>
> 	//other diag_printf was called
>
> The following is the dump of the code.
>
>      2397c:       e3040ffc        movw    r0, #20476      ; 0x4ffc
>    23980:       e3400005        movt    r0, #5  ; 0x5
>    23984:       eb005229        bl      38230 <diag_printf>
> //string pointer points(r0) to 0x54ffc
>    23988:       e3040014        movw    r0, #16404      ; 0x4014
>    2398c:       e3400005        movt    r0, #5  ; 0x5
>    23990:       eb005226        bl      38230 <diag_printf>
> //string pointer points(r0) to 0x54014, it returns to the origin address
> of .rodata,where stores all the strings.
> 	
> //actrually this pointer should point to an address behind 0x54ffc.
>
>
>
> Disassembly of section .rodata:
> 00054008 <__func__.3237-0x18fc>:
>    54008:       636c6557        
>    5400c:       20656d6f       
>    54010:       46206f74        
>    54014:       73656572        
>
>
> And arm-none-eabi- toolchain 2008q3 release could compile this code
> correctly.
>
> But we still want to know the reason of this problem. We hope you could
> help us.
>   

I actually have no explanation for the behavior. I also posted to the 
codesourcery list, but didn't get an answer. To continue development I 
switched to the arm toolchain from zylin, and now I'm working with both 
the new codesourcery release and the zylin toolchain, which both don't 
show this problem. So unfortunately, I cannot really help you.

Simon


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