Re: [avr-gcc-list] Link script question

[Dave N6NZ]

Gre7g Luterman wrote:
> From: Dave N6NZ <address@hidden> To: Gre7g Luterman
> <address@hidden> Cc: address@hidden Sent: Friday,
> October 10, 2008 11:02:21 AM Subject: Re: [avr-gcc-list] Link script
> question
>
> > > That would work, of course, but I'd have to designate a constant 
> > > address for the block, right?
> > No, not at all. That's the point of putting it in the linker script
> > and letting the linker compute the address.
> >
> > > The script as I have it now, automagically selects the first
> > > available block after my code. I really like having this done
> > > automatically for me.
> > And that is exactly what this does.  Take a look at the linker
> > script and how it works.  All my addition does is declare a named
> > section that starts at exactly the place that your
> > __user_prog_start symbol is defined.  It's really your solution,
> > but with an additional name that you can use as an attribute to a
> > data section.
>
> Well, I don't get it. I tried sticking your solution in and I get:
>
> ld.exe:mega32.ld:177: syntax error
>
> Obviously I'm missing something. Your section definitions don't look
> like the others in the script. I'll attach the patched script to this
> e-mail. Perhaps someone can correct the syntax error and show me what
> I'm missing.

OK, well first let me say that I am not a linker script guru, I simply 
manage to get by.

I think the syntax error is coming from two things, the ';' terminating 
the line, and the '*.('.  I don't think the ';' should be at the end of 
a section call out, just at the end of linker expressions, and the 
period in *.( is extraneous, I believe.

Secondly, I think the .userprog section should be inside the braces for 
the data section to accomplish what you want.  (I'm a little fuzzy here, 
though, so double check the documentation.)  Also, I think it should be 
called out as *(.userprog), which says: "any file, the section
'.userprog'", on the assumption that you don't have any '.userprog.foo' 
sections that you want to pick up with a *(.userprog.*) call out.

Here is your file, tweaked.

-dave

> Gre7g

/* Default linker script, for normal executables */
OUTPUT_FORMAT("elf32-avr","elf32-avr","elf32-avr")
OUTPUT_ARCH(avr:1)
MEMORY
{
  text         (rx) : ORIGIN = 0x000000, LENGTH = 0x7D00
  changes      (rx) : ORIGIN = 0x007D00, LENGTH = 0x0080
  update       (rx) : ORIGIN = 0x007D80, LENGTH = 0x0280
  data       (rw!x) : ORIGIN = 0x800060, LENGTH = 0x0800
  eeprom     (rw!x) : ORIGIN = 0x810000, LENGTH = 0x03FF
  eelayver   (rw!x) : ORIGIN = 0x8103FF, LENGTH = 0x0001
}
SECTIONS
{
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  .hash          : { *(.hash)           }
  .dynsym        : { *(.dynsym)         }
  .dynstr        : { *(.dynstr)         }
  .gnu.version   : { *(.gnu.version)    }
  .gnu.version_d   : { *(.gnu.version_d)        }
  .gnu.version_r   : { *(.gnu.version_r)        }
  .rel.init      : { *(.rel.init)               }
  .rela.init     : { *(.rela.init)      }
  .rel.text      :
    {
      *(.rel.text)
      *(.rel.text.*)
      *(.rel.gnu.linkonce.t*)
    }
  .rela.text     :
    {
      *(.rela.text)
      *(.rela.text.*)
      *(.rela.gnu.linkonce.t*)
    }
  .rel.fini      : { *(.rel.fini)               }
  .rela.fini     : { *(.rela.fini)      }
  .rel.rodata    :
    {
      *(.rel.rodata)
      *(.rel.rodata.*)
      *(.rel.gnu.linkonce.r*)
    }
  .rela.rodata   :
    {
      *(.rela.rodata)
      *(.rela.rodata.*)
      *(.rela.gnu.linkonce.r*)
    }
  .rel.data      :
    {
      *(.rel.data)
      *(.rel.data.*)
      *(.rel.gnu.linkonce.d*)
    }
  .rela.data     :
    {
      *(.rela.data)
      *(.rela.data.*)
      *(.rela.gnu.linkonce.d*)
    }
  .rel.ctors     : { *(.rel.ctors)      }
  .rela.ctors    : { *(.rela.ctors)     }
  .rel.dtors     : { *(.rel.dtors)      }
  .rela.dtors    : { *(.rela.dtors)     }
  .rel.got       : { *(.rel.got)                }
  .rela.got      : { *(.rela.got)               }
  .rel.bss       : { *(.rel.bss)                }
  .rela.bss      : { *(.rela.bss)               }
  .rel.plt       : { *(.rel.plt)                }
  .rela.plt      : { *(.rela.plt)               }
  /* Internal text space or external memory.  */
  .changes :
  {
    changes_start = . ;
    *(.changes)
    changes_end = . ;
  } > changes
  .update :
  {
    update_start = . ;
    *(.update)
    update_end = . ;
  } > update
  .text :
  {
    *(.vectors)
    KEEP(*(.vectors))
    /* For data that needs to reside in the lower 64k of progmem.  */
    *(.progmem.gcc*)
    *(.progmem*)
    . = ALIGN(2);
     __trampolines_start = . ;
    /* The jump trampolines for the 16-bit limited relocs will reside here.  */
    *(.trampolines)
    *(.trampolines*)
     __trampolines_end = . ;
    /* For future tablejump instruction arrays for 3 byte pc devices.
       We don't relax jump/call instructions within these sections.  */
    *(.jumptables)
    *(.jumptables*)
    /* For code that needs to reside in the lower 128k progmem.  */
    *(.lowtext)
    *(.lowtext*)
     __ctors_start = . ;
     *(.ctors)
     __ctors_end = . ;
     __dtors_start = . ;
     *(.dtors)
     __dtors_end = . ;
    KEEP(SORT(*)(.ctors))
    KEEP(SORT(*)(.dtors))
    /* From this point on, we don't bother about wether the insns are
       below or above the 16 bits boundary.  */
    *(.init0)  /* Start here after reset.  */
    KEEP (*(.init0))
    *(.init1)
    KEEP (*(.init1))
    *(.init2)  /* Clear __zero_reg__, set up stack pointer.  */
    KEEP (*(.init2))
    *(.init3)
    KEEP (*(.init3))
    *(.init4)  /* Initialize data and BSS.  */
    KEEP (*(.init4))
    *(.init5)
    KEEP (*(.init5))
    *(.init6)  /* C++ constructors.  */
    KEEP (*(.init6))
    *(.init7)
    KEEP (*(.init7))
    *(.init8)
    KEEP (*(.init8))
    *(.init9)  /* Call main().  */
    KEEP (*(.init9))
    *(.text)
    . = ALIGN(2);
    *(.text.*)
    . = ALIGN(2);
    *(.fini9)  /* _exit() starts here.  */
    KEEP (*(.fini9))
    *(.fini8)
    KEEP (*(.fini8))
    *(.fini7)
    KEEP (*(.fini7))
    *(.fini6)  /* C++ destructors.  */
    KEEP (*(.fini6))
    *(.fini5)
    KEEP (*(.fini5))
    *(.fini4)
    KEEP (*(.fini4))
    *(.fini3)
    KEEP (*(.fini3))
    *(.fini2)
    KEEP (*(.fini2))
    *(.fini1)
    KEEP (*(.fini1))
    *(.fini0)  /* Infinite loop after program termination.  */
    KEEP (*(.fini0))
     _etext = . ;
  }  > text
  .data   : AT (ADDR (.text) + SIZEOF (.text))
  {
     PROVIDE (__data_start = .) ;
    *(.data)
    *(.data*)
    *(.rodata)  /* We need to include .rodata here if gcc is used */
    *(.rodata*) /* with -fdata-sections.  */
    *(.gnu.linkonce.d*)
    . = ALIGN(2);
     _edata = . ;
     PROVIDE (__data_end = .) ;
     . = ALIGN(128);
     __user_prog_start = .;
     *(.userprog) 
  }  > data
  /* User-programming space */
  . = _etext + SIZEOF(.data);
  .bss  SIZEOF(.data) + ADDR(.data):
  {
     PROVIDE (__bss_start = .) ;
    *(.bss)
    *(.bss*)
    *(COMMON)
     PROVIDE (__bss_end = .) ;
  }  > data
   __data_load_start = LOADADDR(.data);
   __data_load_end = __data_load_start + SIZEOF(.data);
  /* Global data not cleared after reset.  */
  .noinit  SIZEOF(.bss) + ADDR(.bss) :
  {
     PROVIDE (__noinit_start = .) ;
    *(.noinit*)
     PROVIDE (__noinit_end = .) ;
     _end = . ;
     PROVIDE (__heap_start = .) ;
  }  > data
  .eeprom  :
  {
    *(.eeprom*)
     __eeprom_end = . ;
  }  > eeprom
  /* Stabs debugging sections.  */
  .stab 0 : { *(.stab) }
  .stabstr 0 : { *(.stabstr) }
  .stab.excl 0 : { *(.stab.excl) }
  .stab.exclstr 0 : { *(.stab.exclstr) }
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  .stab.indexstr 0 : { *(.stab.indexstr) }
  .comment 0 : { *(.comment) }
  /* DWARF debug sections.
     Symbols in the DWARF debugging sections are relative to the beginning
     of the section so we begin them at 0.  */
  /* DWARF 1 */
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  /* GNU DWARF 1 extensions */
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  /* DWARF 2 */
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}