AVR32795: Using the GNU Linker Scripts on AVR UC3 ... - Atmel

6.1.2 Related examples in <strong>the</strong> software framework
32158A-AVR-01/11
<strong>AVR32795</strong>
• drivers/flashc/flash_example/: Controlling <strong>the</strong> location of a variable in flash
• drivers/cpu/mpu/example/: Controlling <strong>the</strong> location of a function in flash
6.2 Controlling <strong>the</strong> location of functions in internal RAM
6.2.1 Process flow
6.2.2 Related examples
A. Define a custom output section, .ram_fcts, with VMA in RAM and LMA in flash:
.ram_fcts :
{
*(.ram_fcts.*)
} >INTRAM AT>FLASH :FLASH
B. Locate a function in a custom section, .ram_fcts:
� Extensions to <strong>the</strong> C language family:
o Declaring attributes of functions
Include all input sections .ram_fcts
Assign a section to a previously defined segment
(cf PHDRS command)
Specify a memory region for <strong>the</strong> .text section LMA
Assign this section’s VMA to <strong>the</strong> INTRAM region of memory
(defined in MEMORY{ })
__attribute__ ((__section__(".ram_fcts"))) void Func(void) {…}
C. The startup routine is responsible for copying <strong>the</strong> .ram_fcts LMA (in flash) to <strong>the</strong>
.ram_fcts VMA (in INTRAM), as is done for <strong>the</strong> .data section.
Examples of a startup routine implementation can be found in <strong>the</strong> AVR Software
Framework under utils/startup_files/gcc/ in ASF v1 and under
utils/startup/startup_uc3.S in ASF v2.
An example using <strong>the</strong> same method can be found here:
AVR32749 Application note: Software Workaround Implementation for <strong>the</strong> Erratum
Flash Read-after-Write for AT32UC3A0512 / AT32UC3A1512 Revision E, H and I.
11