circuitpython/ports/raspberrypi/link.ld
Jeff Epler 510890b207
Enable squeezing property storage in flash
.. and enable it on atmel-samd and raspberrypi. On trinket_m0 this saves
96 net bytes of flash. There are 216 bytes actually saved by reducing
the flash storage size of the property descriptors, but added code in
several paths takes back over half of the 'raw savings'.

By organizing the "get-only" and "get-set" (but no delete) properties
each in a different section, we can represent then more efficiently.

Testing performed: that a get-only property can still be gotten but
can't be set or deleted; that a get-set property can sill be gotten or
set but can't be deleted.  Tested on pygamer.

Because this requires linker file support, I only enabled it on two of
the ports.
2022-05-03 08:48:53 -05:00

294 lines
7.6 KiB
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/* Based on GCC ARM embedded samples.
Defines the following symbols for use by code:
__exidx_start
__exidx_end
__etext
__data_start__
__preinit_array_start
__preinit_array_end
__init_array_start
__init_array_end
__fini_array_start
__fini_array_end
__data_end__
__bss_start__
__bss_end__
__end__
end
__HeapLimit
__StackLimit
__StackTop
__stack (== StackTop)
*/
MEMORY
{
FLASH_FIRMWARE (rx) : ORIGIN = 0x10000000, LENGTH = 1020k
RAM (rwx) : ORIGIN = 0x20000000, LENGTH = 256k
SCRATCH_X (rwx) : ORIGIN = 0x20040000, LENGTH = 4k
SCRATCH_Y (rwx) : ORIGIN = 0x20041000, LENGTH = 4k
}
ENTRY(_entry_point)
SECTIONS
{
/* Second stage bootloader is prepended to the image. It must be 256 bytes big
and checksummed. It is usually built by the boot_stage2 target
in the Pico SDK
*/
.flash_begin : {
__flash_binary_start = .;
} > FLASH_FIRMWARE
.boot2 : {
__boot2_start__ = .;
KEEP (*(.boot2))
__boot2_end__ = .;
} > FLASH_FIRMWARE
ASSERT(__boot2_end__ - __boot2_start__ == 256,
"ERROR: Pico second stage bootloader must be 256 bytes in size")
/* The second stage will always enter the image at the start of .text.
The debugger will use the ELF entry point, which is the _entry_point
symbol if present, otherwise defaults to start of .text.
This can be used to transfer control back to the bootrom on debugger
launches only, to perform proper flash setup.
*/
.text : {
__logical_binary_start = .;
KEEP (*(.vectors))
KEEP (*(.binary_info_header))
__binary_info_header_end = .;
KEEP (*(.reset))
/* TODO revisit this now memset/memcpy/float in ROM */
/* bit of a hack right now to exclude all floating point and time critical (e.g. memset, memcpy) code from
* FLASH ... we will include any thing excluded here in .data below by default */
*(.init)
__property_getter_start = .;
*(.property_getter)
__property_getter_end = .;
__property_getset_start = .;
*(.property_getset)
__property_getset_end = .;
*(EXCLUDE_FILE(*libgcc.a: *libc.a:*lib_a-mem*.o *libm.a:) .text*)
*(.fini)
/* Pull all c'tors into .text */
*crtbegin.o(.ctors)
*crtbegin?.o(.ctors)
*(EXCLUDE_FILE(*crtend?.o *crtend.o) .ctors)
*(SORT(.ctors.*))
*(.ctors)
/* Followed by destructors */
*crtbegin.o(.dtors)
*crtbegin?.o(.dtors)
*(EXCLUDE_FILE(*crtend?.o *crtend.o) .dtors)
*(SORT(.dtors.*))
*(.dtors)
*(.eh_frame*)
. = ALIGN(4);
} > FLASH_FIRMWARE
.rodata : {
*(EXCLUDE_FILE(*libgcc.a: *libc.a:*lib_a-mem*.o *libm.a:) .rodata*)
. = ALIGN(4);
*(SORT_BY_ALIGNMENT(SORT_BY_NAME(.flashdata*)))
. = ALIGN(4);
} > FLASH_FIRMWARE
.ARM.extab :
{
*(.ARM.extab* .gnu.linkonce.armextab.*)
} > FLASH_FIRMWARE
__exidx_start = .;
.ARM.exidx :
{
*(.ARM.exidx* .gnu.linkonce.armexidx.*)
} > FLASH_FIRMWARE
__exidx_end = .;
/* Machine inspectable binary information */
. = ALIGN(4);
__binary_info_start = .;
.binary_info :
{
KEEP(*(.binary_info.keep.*))
*(.binary_info.*)
} > FLASH_FIRMWARE
__binary_info_end = .;
. = ALIGN(4);
/* End of .text-like segments */
__etext = .;
.ram_vector_table (COPY): {
*(.ram_vector_table)
} > RAM
.data : {
__data_start__ = .;
*(vtable)
*(.time_critical*)
/* remaining .text and .rodata; i.e. stuff we exclude above because we want it in RAM */
*(.text*)
. = ALIGN(4);
*(.rodata*)
. = ALIGN(4);
*(.data*)
. = ALIGN(4);
*(.after_data.*)
. = ALIGN(4);
/* preinit data */
PROVIDE_HIDDEN (__mutex_array_start = .);
KEEP(*(SORT(.mutex_array.*)))
KEEP(*(.mutex_array))
PROVIDE_HIDDEN (__mutex_array_end = .);
. = ALIGN(4);
/* preinit data */
PROVIDE_HIDDEN (__preinit_array_start = .);
KEEP(*(SORT(.preinit_array.*)))
KEEP(*(.preinit_array))
PROVIDE_HIDDEN (__preinit_array_end = .);
. = ALIGN(4);
/* init data */
PROVIDE_HIDDEN (__init_array_start = .);
KEEP(*(SORT(.init_array.*)))
KEEP(*(.init_array))
PROVIDE_HIDDEN (__init_array_end = .);
. = ALIGN(4);
/* finit data */
PROVIDE_HIDDEN (__fini_array_start = .);
*(SORT(.fini_array.*))
*(.fini_array)
PROVIDE_HIDDEN (__fini_array_end = .);
*(.jcr)
. = ALIGN(4);
/* All data end */
__data_end__ = .;
} > RAM AT> FLASH_FIRMWARE
.itcm :
{
. = ALIGN(4);
*(.itcm.*)
. = ALIGN(4);
} > RAM AT> FLASH_FIRMWARE
_ld_itcm_destination = ADDR(.itcm);
_ld_itcm_flash_copy = LOADADDR(.itcm);
_ld_itcm_size = SIZEOF(.itcm);
.dtcm_data :
{
. = ALIGN(4);
*(.dtcm_data.*)
. = ALIGN(4);
} > RAM AT> FLASH_FIRMWARE
_ld_dtcm_data_destination = ADDR(.dtcm_data);
_ld_dtcm_data_flash_copy = LOADADDR(.dtcm_data);
_ld_dtcm_data_size = SIZEOF(.dtcm_data);
.dtcm_bss :
{
. = ALIGN(4);
*(.dtcm_bss.*)
. = ALIGN(4);
} > RAM AT> RAM
_ld_dtcm_bss_start = ADDR(.dtcm_bss);
_ld_dtcm_bss_size = SIZEOF(.dtcm_bss);
.uninitialized_data (COPY): {
. = ALIGN(4);
*(.uninitialized_data*)
} > RAM
/* Start and end symbols must be word-aligned */
.scratch_x : {
__scratch_x_start__ = .;
*(.scratch_x.*)
. = ALIGN(4);
__scratch_x_end__ = .;
} > SCRATCH_X AT > FLASH_FIRMWARE
__scratch_x_source__ = LOADADDR(.scratch_x);
.scratch_y : {
__scratch_y_start__ = .;
*(.scratch_y.*)
. = ALIGN(4);
__scratch_y_end__ = .;
} > SCRATCH_Y AT > FLASH_FIRMWARE
__scratch_y_source__ = LOADADDR(.scratch_y);
.bss : {
. = ALIGN(4);
__bss_start__ = .;
*(SORT_BY_ALIGNMENT(SORT_BY_NAME(.bss*)))
*(COMMON)
. = ALIGN(4);
__bss_end__ = .;
} > RAM
.heap (COPY):
{
__end__ = .;
end = __end__;
*(.heap*)
__HeapLimit = .;
} > RAM
/* .stack*_dummy section doesn't contains any symbols. It is only
* used for linker to calculate size of stack sections, and assign
* values to stack symbols later
*
* stack1 section may be empty/missing if platform_launch_core1 is not used */
/* by default we put core 0 stack at the end of scratch Y, so that if core 1
* stack is not used then all of SCRATCH_X is free.
*/
.stack1_dummy (COPY):
{
*(.stack1*)
} > SCRATCH_X
.stack_dummy (COPY):
{
*(.stack*)
} > SCRATCH_Y
.flash_end : {
__flash_binary_end = .;
} > FLASH_FIRMWARE
/* stack limit is poorly named, but historically is maximum heap ptr */
__StackLimit = ORIGIN(RAM) + LENGTH(RAM);
__StackOneTop = ORIGIN(SCRATCH_X) + LENGTH(SCRATCH_X);
__StackTop = ORIGIN(SCRATCH_Y) + LENGTH(SCRATCH_Y);
__StackOneBottom = __StackOneTop - SIZEOF(.stack1_dummy);
__StackBottom = __StackTop - SIZEOF(.stack_dummy);
PROVIDE(__stack = __StackTop);
/* Check if data + heap + stack exceeds RAM limit */
ASSERT(__StackLimit >= __HeapLimit, "region RAM overflowed")
ASSERT( __binary_info_header_end - __logical_binary_start <= 256, "Binary info must be in first 256 bytes of the binary")
/* todo assert on extra code */
}