Re: [avr-libc-dev] bootloader with boot.h

[Björn Haase]

Rok Markovic wrote on Freitag, 9. September 2005 22:58 :
> Hi
>
> I have a problem with programing the bootloader. I am using atmega128,
> avrlibc 1.2.5, avr-gcc 4.0.1, binutils 2.16.1. Linker report problem
> with undefined reference  'Y'. This problem is in function
> boot_page_erase(addr) from boot .h. I will explain my problem on two
> examples.
>
> First instance of call boot_page_erase():
>
>   51:program.c     ****       boot_page_erase (70);
>   80                  .LM2:
>   81                  /* #NOAPP */
>   82 0008 23E0                ldi r18,lo8(3)
>   83 000a 86E4                ldi r24,lo8(70)
>   84 000c 90E0                ldi r25,hi8(70)
>   85 000e A0E0                ldi r26,hlo8(70)
>   86 0010 B0E0                ldi r27,hhi8(70)
>   87                  /* #APP */
>   88 0012 FC01                movw r30, r24
>   89 0014 A093 5B00           sts  91, r26
>   90 0018 2093 6800           sts 104, r18
>   91 001c E895                spm
>
>
> When I am calling this function for second time compiler produces this:
>
>  131 004e C8E6                ldi r28,lo8(104)
>  132 0050 D0E0                ldi r29,hi8(104)
>  133 0052 93E0                ldi r25,lo8(3)
>  134 0054 A8E6                ldi r26,lo8(104)
>  135 0056 B0E0                ldi r27,hi8(104)
>  136                  .L8:
>   69:program.c     ****                       // erase only main section 
> (bootloader
> protection) 70:program.c     ****                     address = 0;
>   71:program.c     ****                       while ( address < 0x1dfff ){
>   72:program.c     ****                               // Perform page erase
>   73:program.c     ****                               boot_page_erase 
> (address);
>  138                  .LM10:
>  139                  /* #APP */
>  140 0058 F901                movw r30, r18
>  141 005a 4093 5B00           sts  91, r20
>  142 005e 9093 0000           sts Y, r25              <<--PROBLEM
>  143 0062 E895                spm
>
>
> Problem is in call sts Y,r25. Compiler loads 104 which is addres of
> SPM_REG but  you cannot write to Y with sts only with st. If you look
> into boot.h there is output operators "=m". What do they stand for. I
> haven't found any documentatio for them. How can you force the compiler
> to do correct code.

Try to implement a change in boot.h so that 
__boot_page_write_extended(address) reads

#define __boot_page_write_extended(address)      \
({                                               \
    __asm__ __volatile__                         \
    (                                            \
        "movw r30, %A3\n\t"                      \
        "sts %5, %C3\n\t"                        \
        "sts %4, %2\n\t"                         \
        "spm\n\t"                                \
        : "=m" (__SPM_REG),                      \
          "=m" (RAMPZ)                           \
        : "r" ((uint8_t)__BOOT_PAGE_WRITE),      \
          "r" ((uint32_t)address),                \
          "i" (&__SPM_REG),                \
          "i" (&RAMPZ)                \
        : "r30", "r31"                           \
    );                                           \
})