128 lines
3.4 KiB
Plaintext
128 lines
3.4 KiB
Plaintext
/*
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* Linker script for the Betaflight N6 OpenBootloader (OBL).
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*
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* Boot ROM behaviour (BOOT0=USER, BOOT1=2):
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* 1. Reads signed FSBL header from XSPI 0x70000000
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* 2. Verifies + copies payload into AXISRAM2 secure starting at
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* 0x34180400 (the 0x400 offset matches `STM32_SigningTool_CLI -align`)
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* 3. Branches to Reset_Handler at the loaded entry point
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*
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* The boot ROM caps @FSBL DFU staging at ~485 KiB empirically — the
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* destination region from 0x34180400 to end of AXISRAM2 secure is 521 KiB
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* but the boot ROM reserves ~36 KiB of scratch. The 480 KiB region below
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* is the safe budget for OBL + flash driver + DFU stack + self-installer.
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*/
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ENTRY(Reset_Handler)
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_Min_Stack_Size = 0x2000; /* 8 KiB — DFU upload buffer + USB ISR + libc */
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MEMORY
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{
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/* Loaded region: signed FSBL slot in AXISRAM2 secure. Boot ROM lands
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* the .stm32 payload here. 64 KiB caps OBL well below the boot-ROM
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* @FSBL DFU staging limit and leaves the rest of AXISRAM2-secure
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* free for any future secure code. */
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RAM (rwx) : ORIGIN = 0x34180400, LENGTH = 64K
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}
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_estack = ORIGIN(RAM) + LENGTH(RAM);
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_sstack = _estack - _Min_Stack_Size;
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SECTIONS
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{
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.isr_vector :
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{
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. = ALIGN(4);
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KEEP(*(.isr_vector))
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. = ALIGN(4);
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} > RAM
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.text :
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{
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. = ALIGN(4);
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*(.text)
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*(.text.*)
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*(.glue_7)
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*(.glue_7t)
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*(.eh_frame)
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. = ALIGN(4);
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} > RAM
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.rodata :
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{
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. = ALIGN(4);
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*(.rodata)
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*(.rodata.*)
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. = ALIGN(4);
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} > RAM
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.ARM.extab :
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{
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*(.ARM.extab* .gnu.linkonce.armextab.*)
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} > RAM
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.ARM :
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{
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__exidx_start = .;
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*(.ARM.exidx*)
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__exidx_end = .;
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} > RAM
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/* Embedded "self" payload: the OBL writes the bytes of its own loaded
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* image to nor0 0x0 during recovery self-install. The payload starts
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* at the FSBL header (0x34180000 in AXISRAM, which is 0x34180400 minus
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* the 0x400 alignment header — but boot ROM only stages from 0x34180400
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* onwards, so the "self" we replicate is the post-header content). The
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* signed header has to be re-applied externally — at install time we
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* read it from nor0 too via memory-mapped XSPI before erase. */
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_self_load_start = ORIGIN(RAM);
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_self_load_end = .; /* updated by linker after .data */
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_sidata = LOADADDR(.data);
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.data :
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{
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. = ALIGN(4);
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_sdata = .;
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*(.data)
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*(.data.*)
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. = ALIGN(4);
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_edata = .;
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} > RAM
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.bss :
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{
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. = ALIGN(4);
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_sbss = .;
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__bss_start__ = .;
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*(.bss)
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*(.bss.*)
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*(COMMON)
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. = ALIGN(4);
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_ebss = .;
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__bss_end__ = .;
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/* End-of-image marker for newlib's _sbrk. We don't use malloc,
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* but linking pulls _sbrk in regardless; satisfy it with a
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* symbol that points past .bss so any incidental allocation
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* lands in unused heap space below the stack reservation. */
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PROVIDE(end = .);
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PROVIDE(_end = .);
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} > RAM
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/* Stack reservation at the top of RAM. Linker fails the build if BSS
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* overflows into the stack region. */
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._stack_reservation :
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{
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. = ALIGN(8);
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. = . + _Min_Stack_Size;
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. = ALIGN(8);
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} > RAM
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/DISCARD/ :
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{
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*(.ARM.attributes)
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*(.comment)
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}
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}
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