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(ld.info)Output Section LMA

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Output section LMA
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   Every section has a virtual address (VMA) and a load address (LMA);
see Note: Basic Script Concepts.  The address expression which may
appear in an output section description sets the VMA (Note: Output
Section Address).

   The linker will normally set the LMA equal to the VMA.  You can
change that by using the `AT' keyword.  The expression LMA that follows
the `AT' keyword specifies the load address of the section.
Alternatively, with `AT>LMA_REGION' expression, you may specify a
memory region for the section's load address. Note: MEMORY.

   This feature is designed to make it easy to build a ROM image.  For
example, the following linker script creates three output sections: one
called `.text', which starts at `0x1000', one called `.mdata', which is
loaded at the end of the `.text' section even though its VMA is
`0x2000', and one called `.bss' to hold uninitialized data at address
`0x3000'.  The symbol `_data' is defined with the value `0x2000', which
shows that the location counter holds the VMA value, not the LMA value.

     SECTIONS
       {
       .text 0x1000 : { *(.text) _etext = . ; }
       .mdata 0x2000 :
         AT ( ADDR (.text) + SIZEOF (.text) )
         { _data = . ; *(.data); _edata = . ;  }
       .bss 0x3000 :
         { _bstart = . ;  *(.bss) *(COMMON) ; _bend = . ;}
     }

   The run-time initialization code for use with a program generated
with this linker script would include something like the following, to
copy the initialized data from the ROM image to its runtime address.
Notice how this code takes advantage of the symbols defined by the
linker script.

     extern char _etext, _data, _edata, _bstart, _bend;
     char *src = &_etext;
     char *dst = &_data;
     
     /* ROM has data at end of text; copy it. */
     while (dst < &_edata) {
       *dst++ = *src++;
     }
     
     /* Zero bss */
     for (dst = &_bstart; dst< &_bend; dst++)
       *dst = 0;