Re: Newlib 1.8.1 vfprintf problem on embedded PowerPC

[Scott Howard <scott@objsw.com>]

Well, it looks like that bug was fixed in 1.8.1 (I was using
newlib-1.8.0 at the time). I don't see a problem with the code below, so
I guess the problem lies elsewhere.

Scott

Roger Williams wrote:
> 
> >>>>> Scott Howard <scott@objsw.com> writes:
> 
>   > Printf works fine, but the startup code supplied with newlib (see
>   > libgloss/rs6000/*crt0.S) doesn't clear memory in the 'sbss'
>   > section to all zeros, it only clears the 'bss' section. This is
>   > what's sending printf etc. into the weeds.
> 
> Well, that would certainly do it.  But this is what my crt0.S looks
> like -- it certainly appears to clear sbss:
> 
>         /* clear bss and sbss */
>         lwz     r6,.Lbss_start(r5)      /* calculate beginning of the BSS */
>         lwz     r7,.Lend(r5)            /* calculate end of the BSS */
>         add     r6,r6,r4                /* adjust pointers */
>         add     r7,r7,r4
> 
>         cmplw   1,r6,r7
>         bc      4,4,.Ldone1
> 
>         subf    r8,r6,r7                /* number of bytes to zero */
>         srwi    r9,r8,2                 /* number of words to zero */
>         mtctr   r9
>         li      r0,0                    /* zero to clear memory */
>         addi    r6,r6,-4                /* adjust so we can use stwu */
> .Lloop:
>         stwu    r0,4(r6)                /* zero bss */
>         bdnz    .Lloop
> 
> .Ldone1:
> 
>         lwz     r6,.Lsbss_start(r5)     /* calculate beginning of the SBSS */
>         lwz     r7,.Lsbss_end(r5)       /* calculate end of the SBSS */
>         add     r6,r6,r4                /* adjust pointers */
>         add     r7,r7,r4
> 
>         cmplw   1,r6,r7
>         bc      4,4,.Ldone
> 
>         subf    r8,r6,r7                /* number of bytes to zero */
>         srwi    r9,r8,2                 /* number of words to zero */
>         mtctr   r9
>         li      r0,0                    /* zero to clear memory */
>         addi    r6,r6,-4                /* adjust so we can use stwu */
> .Lloop2:
>         stwu    r0,4(r6)                /* zero bss */
>         bdnz    .Lloop2
> 
> .Ldone:
> 
> My map file shows
> 
>                 0x0002c464                PROVIDE (__sbss_start, .)
>                 0x0002c46c                PROVIDE (__sbss_end, .)
>                 0x0002c470                PROVIDE (__bss_start, .)
>                 0x0002c498                PROVIDE (end, .)
> 
> which seems about right for my test code.  Do you see a bug?
> 
> --
> Roger Williams                         finger me for my PGP public key
> Coelacanth Engineering Inc    consulting & turnkey product development
> Middleborough, Massachusetts           wireless * datacomm * DSP * ATE
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