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Merged
merged 3 commits into from
Feb 28, 2019
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Update the bootstrap document with 2-region memory model #951

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5bdc302
Update the bootstrap document with 2-region memory model
Feb 14, 2019
c5f8dc2
Add aligment and unitialized section in GCC linker script sample
Feb 15, 2019
586b7c3
Edit bootstrap.md
Feb 26, 2019
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101 changes: 55 additions & 46 deletions docs/porting/target/bootstrap.md
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Original file line number Diff line number Diff line change
Expand Up @@ -18,7 +18,7 @@ If you are updating your own linker script, you must:

- Reserve space for the RAM vector table.
- Define the heap region:
- Arm - The heap starts immediately after the region `RW_IRAM1` and ends at the start of the `ARM_LIB_STACK` region.
- Arm - The heap is the `ARM_LIB_HEAP` region.
- GCC_ARM - The heap starts at the symbol `__end__` and ends at the `__HeapLimit` symbol.
- IAR - The heap is the `HEAP` region.
- Define the boot stack region:
Expand All @@ -38,43 +38,44 @@ Arm linker script template:

/* Device specific values */

#define ROM_START 0x08000000
#define ROM_SIZE 0x200000
#define RAM_START 0x20000000
#define RAM_SIZE 0x30000
#define VECTORS 107 /* This value must match NVIC_NUM_VECTORS */
/* Tools provide -DMBED_ROM_START=xxx -DMBED_ROM_SIZE=xxx -DMBED_RAM_START=xxx -DMBED_RAM_SIZE=xxx */

#define VECTORS xx /* This value must match NVIC_NUM_VECTORS */

/* Common - Do not change */

#if !defined(MBED_APP_START)
#define MBED_APP_START ROM_START
#define MBED_APP_START MBED_ROM_START
#endif

#if !defined(MBED_APP_SIZE)
#define MBED_APP_SIZE ROM_SIZE
#define MBED_APP_SIZE MBED_ROM_SIZE
#endif

#if !defined(MBED_BOOT_STACK_SIZE)
/* This value is normally defined by the tools
to 0x400 for mbed 2 and 0x1000 for mbed 5 */
#define MBED_BOOT_STACK_SIZE 0x1000
/* This value is normally defined by the tools to 0x1000 for bare metal and 0x400 for RTOS */
#define MBED_BOOT_STACK_SIZE 0x400
#endif

/* Round up VECTORS_SIZE to 8 bytes */
#define VECTORS_SIZE (((VECTORS * 4) + 7) AND ~7)
#define VECTORS_SIZE (((VECTORS * 4) + 7) AND ~7)

LR_IROM1 MBED_APP_START MBED_APP_SIZE {
LR_IROM1 MBED_APP_START MBED_APP_SIZE {

ER_IROM1 MBED_APP_START MBED_APP_SIZE {
ER_IROM1 MBED_APP_START MBED_APP_SIZE {
*.o (RESET, +First)
*(InRoot$$Sections)
.ANY (+RO)
}

RW_IRAM1 (RAM_START + VECTORS_SIZE) (RAM_SIZE - VECTORS_SIZE - MBED_BOOT_STACK_SIZE) { ; RW data
RW_IRAM1 (RAM_START + VECTORS_SIZE) { ; RW data
.ANY (+RW +ZI)
}
ARM_LIB_STACK (RAM_START + RAM_SIZE) EMPTY -MBED_BOOT_STACK_SIZE { ; Stack region growing down

ARM_LIB_HEAP AlignExpr(+0, 16) EMPTY (MBED_RAM_START + MBED_RAM_SIZE - MBED_BOOT_STACK_SIZE - AlignExpr(ImageLimit(RW_IRAM1), 16)) { ; Heap growing up
}

ARM_LIB_STACK (RAM_START + RAM_SIZE) EMPTY -MBED_BOOT_STACK_SIZE { ; Stack region growing down
}
}
```
Expand All @@ -84,33 +85,31 @@ IAR linker script template:
```
/* Device specific values */

define symbol ROM_START = 0x08000000;
define symbol ROM_SIZE = 0x200000;
define symbol RAM_START = 0x20000000;
define symbol RAM_SIZE = 0x30000;
define symbol VECTORS = 107; /* This value must match NVIC_NUM_VECTORS */
/* Tools provide -DMBED_ROM_START=xxx -DMBED_ROM_SIZE=xxx -DMBED_RAM_START=xxx -DMBED_RAM_SIZE=xxx */

define symbol VECTORS = xx; /* This value must match NVIC_NUM_VECTORS */
define symbol HEAP_SIZE = 0x10000;

/* Common - Do not change */

if (!isdefinedsymbol(MBED_APP_START)) {
define symbol MBED_APP_START = ROM_START;
define symbol MBED_APP_START = MBED_ROM_START;
}

if (!isdefinedsymbol(MBED_APP_SIZE)) {
define symbol MBED_APP_SIZE = ROM_SIZE;
define symbol MBED_APP_SIZE = MBED_ROM_SIZE;
}

if (!isdefinedsymbol(MBED_BOOT_STACK_SIZE)) {
/* This value is normally defined by the tools
to 0x400 for mbed 2 and 0x1000 for mbed 5 */
define symbol MBED_BOOT_STACK_SIZE = 0x1000;
to 0x1000 for bare metal and 0x400 for RTOS */
define symbol MBED_BOOT_STACK_SIZE = 0x400;
}

/* Round up VECTORS_SIZE to 8 bytes */
define symbol VECTORS_SIZE = ((VECTORS * 4) + 7) & ~7;
define symbol RAM_REGION_START = RAM_START + VECTORS_SIZE;
define symbol RAM_REGION_SIZE = RAM_SIZE - VECTORS_SIZE;
define symbol RAM_REGION_START = MBED_RAM_START + VECTORS_SIZE;
define symbol RAM_REGION_SIZE = MBED_RAM_SIZE - VECTORS_SIZE;

define memory mem with size = 4G;
define region ROM_region = mem:[from MBED_APP_START size MBED_APP_SIZE];
Expand All @@ -135,26 +134,24 @@ GCC linker script template:
```
/* Device specific values */

#define ROM_START 0x08000000
#define ROM_SIZE 0x200000
#define RAM_START 0x20000000
#define RAM_SIZE 0x30000
#define VECTORS 107 /* This value must match NVIC_NUM_VECTORS */
/* Tools provide -DMBED_ROM_START=xxx -DMBED_ROM_SIZE=xxx -DMBED_RAM_START=xxx -DMBED_RAM_SIZE=xxx */

#define VECTORS xx /* This value must match NVIC_NUM_VECTORS */

/* Common - Do not change */

#if !defined(MBED_APP_START)
#define MBED_APP_START ROM_START
#define MBED_APP_START MBED_ROM_START
#endif

#if !defined(MBED_APP_SIZE)
#define MBED_APP_SIZE ROM_SIZE
#define MBED_APP_SIZE MBED_ROM_SIZE
#endif

#if !defined(MBED_BOOT_STACK_SIZE)
/* This value is normally defined by the tools
to 0x400 for mbed 2 and 0x1000 for mbed 5 */
#define MBED_BOOT_STACK_SIZE 0x1000
to 0x1000 for bare metal and 0x400 for RTOS */
#define MBED_BOOT_STACK_SIZE 0x400
#endif

/* Round up VECTORS_SIZE to 8 bytes */
Expand All @@ -163,7 +160,7 @@ GCC linker script template:
MEMORY
{
FLASH (rx) : ORIGIN = MBED_APP_START, LENGTH = MBED_APP_SIZE
RAM (rwx) : ORIGIN = RAM_START + VECTORS_SIZE, LENGTH = RAM_SIZE - VECTORS_SIZE
RAM (rwx) : ORIGIN = MBED_RAM_START + VECTORS_SIZE, LENGTH = MBED_RAM_SIZE - VECTORS_SIZE
}

/* Linker script to place sections and symbol values. Should be used together
Expand Down Expand Up @@ -237,50 +234,62 @@ SECTIONS

/* Location counter can end up 2byte aligned with narrow Thumb code but
__etext is assumed by startup code to be the LMA of a section in RAM
which must be 4byte aligned */
__etext = ALIGN (4);
which must be 8-byte aligned */
__etext = ALIGN (8);

.data : AT (__etext)
{
__data_start__ = .;
*(vtable)
*(.data*)

. = ALIGN(4);
. = ALIGN(8);
/* preinit data */
PROVIDE_HIDDEN (__preinit_array_start = .);
KEEP(*(.preinit_array))
PROVIDE_HIDDEN (__preinit_array_end = .);

. = ALIGN(4);
. = ALIGN(8);
/* init data */
PROVIDE_HIDDEN (__init_array_start = .);
KEEP(*(SORT(.init_array.*)))
KEEP(*(.init_array))
PROVIDE_HIDDEN (__init_array_end = .);


. = ALIGN(4);
. = ALIGN(8);
/* finit data */
PROVIDE_HIDDEN (__fini_array_start = .);
KEEP(*(SORT(.fini_array.*)))
KEEP(*(.fini_array))
PROVIDE_HIDDEN (__fini_array_end = .);

KEEP(*(.jcr*))
. = ALIGN(4);
. = ALIGN(8);
/* All data end */
__data_end__ = .;

} > RAM

/* Uninitialized data section
* This region is not initialized by the C/C++ library and can be used to
* store state across soft reboots. */
.uninitialized (NOLOAD):
{
. = ALIGN(32);
__uninitialized_start = .;
*(.uninitialized)
KEEP(*(.keep.uninitialized))
. = ALIGN(32);
__uninitialized_end = .;
} > RAM

.bss :
{
. = ALIGN(4);
. = ALIGN(8);
__bss_start__ = .;
*(.bss*)
*(COMMON)
. = ALIGN(4);
. = ALIGN(8);
__bss_end__ = .;
} > RAM

Expand Down