circuitpython/atmel-samd/boards/samd21x18-bootloader-crystalless.ld
Scott Shawcroft 266be30777 atmel-samd: Introduce a nvm module for non-volatile byte-level memory access. (#203)
* atmel-samd: Introduce a nvm module for non-volatile byte-level memory access.

This allows for persisting small configuration values even when the file system
is read-only from CircuitPython.

Fixes #160

* Review feedback:
* Add tests.
* Fix non-zero index.
* Fix len()
2017-08-25 16:00:27 -04:00

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/*
GNU linker script for SAMD21
*/
/* Specify the memory areas */
MEMORY
{
/* Leave 8KiB for the bootloader, 256b for persistent config (clock), 64k for the flash file system and 256b for the user config. */
FLASH (rx) : ORIGIN = 0x00000000+0x2000, LENGTH = 0x00040000 - 0x2000 - 0x100 - 0x010000 - 0x100
RAM (xrw) : ORIGIN = 0x20000000, LENGTH = 0x008000 /* 32 KiB */
}
/* top end of the stack */
_estack = ORIGIN(RAM) + LENGTH(RAM);
/* define output sections */
SECTIONS
{
/* The program code and other data goes into FLASH */
.text :
{
. = ALIGN(4);
_sfixed = .;
KEEP(*(.vectors)) /* isr vector table */
*(.text) /* .text sections (code) */
*(.text*) /* .text* sections (code) */
*(.rodata) /* .rodata sections (constants, strings, etc.) */
*(.rodata*) /* .rodata* sections (constants, strings, etc.) */
. = ALIGN(4);
_etext = .; /* define a global symbol at end of code */
} >FLASH
.ARM.exidx :
{
*(.ARM.exidx*)
*(.gnu.linkonce.armexidx.*)
_sidata = .; /* This is used by the startup in order to initialize the .data section */
} > FLASH
/* This is the initialized data section
The program executes knowing that the data is in the RAM
but the loader puts the initial values in the FLASH (inidata).
It is one task of the startup to copy the initial values from FLASH to RAM. */
.data : AT ( _sidata )
{
. = ALIGN(4);
_srelocate = .; /* create a global symbol at data start; used by startup code in order to initialize the .data section in RAM */
*(.ramfunc)
*(.ramfunc*)
*(.data) /* .data sections */
*(.data*) /* .data* sections */
. = ALIGN(4);
_erelocate = .; /* define a global symbol at data end; used by startup code in order to initialize the .data section in RAM */
} >RAM
/* Uninitialized data section */
.bss :
{
. = ALIGN(4);
_sbss = .;
_szero = .; /* define a global symbol at bss start; used by startup code */
*(.bss)
*(.bss*)
*(COMMON)
. = ALIGN(4);
_ezero = .; /* define a global symbol at bss end; used by startup code */
_ebss = .;
} >RAM
/* this just checks there is enough RAM for a minimal stack */
.stack :
{
. = ALIGN(4);
. = . + 0x800; /* Reserve a minimum of 2K for the stack. */
. = ALIGN(4);
} >RAM
.ARM.attributes 0 : { *(.ARM.attributes) }
}