Add ability to build combined images

CMakeLists.txt

@@ -1,10 +1,36 @@
+# Derived from the Pico SDK, which carries the following
+# LICENSE.txt:
+# Copyright 2020 (c) 2020 Raspberry Pi (Trading) Ltd.
+#
+# Redistribution and use in source and binary forms, with or without modification, are permitted provided that the
+# following conditions are met:
+#
+# 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following
+#    disclaimer.
+#
+# 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following
+#    disclaimer in the documentation and/or other materials provided with the distribution.
+#
+# 3. Neither the name of the copyright holder nor the names of its contributors may be used to endorse or promote products
+#    derived from this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
+# INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+# DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+# SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+# WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+# THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
 cmake_minimum_required(VERSION 3.13)
 
 include(pico_sdk_import.cmake)
 
 project(picowota C CXX ASM)
+
 set(CMAKE_C_STANDARD 11)
 set(CMAKE_CXX_STANDARD 17)
+
 pico_sdk_init()
 
 add_executable(picowota
@@ -13,13 +39,24 @@ add_executable(picowota
 	tcp_comm.c
 )
 
-pico_enable_stdio_usb(picowota 1)
+function(target_cl_options option)
+    target_compile_options(picowota PRIVATE ${option})
+    target_link_options(picowota PRIVATE ${option})
+endfunction()
+
+target_cl_options("-Wall")
+target_cl_options("-Os")
+target_cl_options("-ffunction-sections")
+target_cl_options("-fdata-sections")
+target_link_options(picowota PRIVATE "LINKER:--gc-sections")
 
 pico_add_extra_outputs(picowota)
-set_target_properties(picowota PROPERTIES COMPILE_FLAGS "-Wall -Os")
 
+# Needed so that lwip can find lwipopts.h
 target_include_directories(picowota PRIVATE ${CMAKE_CURRENT_LIST_DIR})
 
+pico_enable_stdio_usb(picowota 1)
+
 add_subdirectory(picowota_reboot)
 
 target_link_libraries(picowota
@@ -34,3 +71,61 @@ target_link_libraries(picowota
 	pico_util
 	picowota_reboot
 )
+
+# Provide a helper to build a standalone target
+function(picowota_build_standalone NAME)
+	get_target_property(PICOWOTA_SRC_DIR picowota SOURCE_DIR)
+	pico_set_linker_script(${NAME} ${PICOWOTA_SRC_DIR}/standalone.ld)
+	pico_add_bin_output(${NAME})
+endfunction()
+
+# Provide a helper to build a combined target
+# The build process is roughly:
+# 1. Build the bootloader, using a special linker script which leaves
+#    two sections to be filled in with the header (.app_hdr) and
+#    app binary (.app_bin)
+# 2. Build the app binary, using a special linker script to set the load
+#    address properly and skip boot2.
+# 3. Calculate the checksum of the app binary
+# 4. Update the header and binary sections in the ELF from 1.
+function(picowota_build_combined NAME)
+	set(APP_BIN ${CMAKE_CURRENT_BINARY_DIR}/${NAME}.bin)
+	set(APP_HDR_BIN ${CMAKE_CURRENT_BINARY_DIR}/${NAME}_hdr.bin)
+	set(COMBINED picowota_${NAME})
+	get_target_property(PICOWOTA_SRC_DIR picowota SOURCE_DIR)
+	get_target_property(PICOWOTA_BIN_DIR picowota BINARY_DIR)
+
+	# The app must be built with the correct linker script (and a .bin)
+	picowota_build_standalone(${NAME})
+
+	# Build the bootloader with the sections to fill in
+	pico_set_linker_script(picowota ${PICOWOTA_SRC_DIR}/bootloader_shell.ld)
+
+	# TODO: The hard-coded address here is a bit nasty
+	add_custom_target(${NAME}_hdr DEPENDS ${APP_BIN})
+	add_custom_command(TARGET ${NAME}_hdr DEPENDS ${APP_BIN}
+		COMMAND ${PICOWOTA_SRC_DIR}/gen_imghdr.py -a 0x1005B000 ${APP_BIN} ${APP_HDR_BIN}
+	)
+
+	add_custom_target(${COMBINED} ALL)
+	add_dependencies(${COMBINED} picowota ${NAME}_hdr ${NAME})
+	add_custom_command(TARGET ${COMBINED} DEPENDS ${APP_HDR_BIN} ${APP_BIN}
+		COMMAND ${CMAKE_OBJCOPY}
+			--update-section .app_hdr=${APP_HDR_BIN}
+			--update-section .app_bin=${APP_BIN} ${PICOWOTA_BIN_DIR}/picowota.elf ${COMBINED}.elf
+	)
+
+	add_custom_command(TARGET ${COMBINED} POST_BUILD
+		COMMAND ${CMAKE_OBJCOPY} -Obinary ${COMBINED}.elf ${COMBINED}.bin
+	)
+
+	if (NOT ELF2UF2_FOUND)
+		set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} ${PICO_SDK_PATH}/tools)
+		find_package(ELF2UF2)
+	endif()
+	if (ELF2UF2_FOUND)
+		add_custom_command(TARGET ${COMBINED} POST_BUILD
+			COMMAND ELF2UF2 ${COMBINED}.elf ${COMBINED}.uf2
+	)
+	endif()
+endfunction()

bootloader.ld

@@ -0,0 +1,258 @@
+/* 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)
+*/
+
+/*
+ * TODO: Hard-code 360k, which is the size I see on my machine with
+ * 'sta' mode and debug printf.
+ * There must be a better way to determine the size dynamically somehow.
+ */
+MEMORY
+{
+    FLASH(rx) : ORIGIN = 0x10000000, LENGTH = 360k
+    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 Raspberry Pi Pico SDK
+    */
+
+    .flash_begin : {
+        __flash_binary_start = .;
+    } > FLASH
+
+    .boot2 : {
+        __boot2_start__ = .;
+        KEEP (*(.boot2))
+        __boot2_end__ = .;
+    } > FLASH
+
+    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.
+    */
+
+    .flashtext : {
+        __logical_binary_start = .;
+        KEEP (*(.vectors))
+        KEEP (*(.binary_info_header))
+        __binary_info_header_end = .;
+        KEEP (*(.reset))
+    }
+
+    .rodata : {
+        /* segments not marked as .flashdata are instead pulled into .data (in RAM) to avoid accidental flash accesses */
+        *(SORT_BY_ALIGNMENT(SORT_BY_NAME(.flashdata*)))
+        . = ALIGN(4);
+    } > FLASH
+
+    .ARM.extab :
+    {
+        *(.ARM.extab* .gnu.linkonce.armextab.*)
+    } > FLASH
+
+    __exidx_start = .;
+    .ARM.exidx :
+    {
+        *(.ARM.exidx* .gnu.linkonce.armexidx.*)
+    } > FLASH
+    __exidx_end = .;
+
+    /* Machine inspectable binary information */
+    . = ALIGN(4);
+    __binary_info_start = .;
+    .binary_info :
+    {
+        KEEP(*(.binary_info.keep.*))
+        *(.binary_info.*)
+    } > FLASH
+    __binary_info_end = .;
+    . = ALIGN(4);
+
+    /* Vector table goes first in RAM, to avoid large alignment hole */
+   .ram_vector_table (COPY): {
+        *(.ram_vector_table)
+    } > RAM
+
+    .text : {
+        __ram_text_start__ = .;
+        *(.init)
+        *(.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);
+        __ram_text_end__ = .;
+    } > RAM AT> FLASH
+    __ram_text_source__ = LOADADDR(.text);
+
+
+    .data : {
+        __data_start__ = .;
+        *(vtable)
+
+        *(.time_critical*)
+
+        . = 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
+    /* __etext is the name of the .data init source pointer (...) */
+    __etext = LOADADDR(.data);
+
+    .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
+    __scratch_x_source__ = LOADADDR(.scratch_x);
+
+    .scratch_y : {
+        __scratch_y_start__ = .;
+        *(.scratch_y.*)
+        . = ALIGN(4);
+        __scratch_y_end__ = .;
+    } > SCRATCH_Y AT > FLASH
+    __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
+
+    /* 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 */
+}
+

bootloader_shell.ld

@@ -0,0 +1,276 @@
+/* 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)
+*/
+
+/*
+ * TODO: Hard-code 360k, which is the max size I see on my machine with
+ * 'sta' mode and debug printf.
+ * There must be a better way to determine the size dynamically somehow.
+ */
+MEMORY
+{
+    FLASH(rx) : ORIGIN = 0x10000000, LENGTH = 360k
+    FLASH_IMGHDR(rx) : ORIGIN = 0x10000000 + 360k, LENGTH = 4k
+    FLASH_APP(rx) : ORIGIN = 0x10000000 + 364k, LENGTH = 2048k - 364k
+    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 Raspberry Pi Pico SDK
+    */
+
+    .flash_begin : {
+        __flash_binary_start = .;
+    } > FLASH
+
+    .boot2 : {
+        __boot2_start__ = .;
+        KEEP (*(.boot2))
+        __boot2_end__ = .;
+    } > FLASH
+
+    ASSERT(__boot2_end__ - __boot2_start__ == 256,
+        "ERROR: Pico second stage bootloader must be 256 bytes in size")
+
+    /*
+     * Name a section for the image header and app binary
+     * In combined builds, the contents will get replaced post-build
+     */
+    .app_hdr : {
+        . = ALIGN(4k);
+	__app_hdr = .;
+	LONG(0xdeaddead)
+	LONG(0)
+	LONG(0xdeaddead)
+    } > FLASH_IMGHDR
+
+    .app_bin : {
+        . = ALIGN(4k);
+	__app_bin = .;
+	LONG(0)
+    } > FLASH_APP
+
+    /* 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)
+        *(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
+
+    .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
+
+    .ARM.extab :
+    {
+        *(.ARM.extab* .gnu.linkonce.armextab.*)
+    } > FLASH
+
+    __exidx_start = .;
+    .ARM.exidx :
+    {
+        *(.ARM.exidx* .gnu.linkonce.armexidx.*)
+    } > FLASH
+    __exidx_end = .;
+
+    /* Machine inspectable binary information */
+    . = ALIGN(4);
+    __binary_info_start = .;
+    .binary_info :
+    {
+        KEEP(*(.binary_info.keep.*))
+        *(.binary_info.*)
+    } > FLASH
+    __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
+
+    .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
+    __scratch_x_source__ = LOADADDR(.scratch_x);
+
+    .scratch_y : {
+        __scratch_y_start__ = .;
+        *(.scratch_y.*)
+        . = ALIGN(4);
+        __scratch_y_end__ = .;
+    } > SCRATCH_Y AT > FLASH
+    __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
+
+    /* 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 */
+}

combined.ld

@@ -0,0 +1,248 @@
+/* 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_BL(rx) : ORIGIN = 0x10000000, LENGTH = 360k
+    FLASH_IMGHDR(rx) : ORIGIN = 0x10000000 + 360k, LENGTH = 4k
+    FLASH_APP(rx) : ORIGIN = 0x10000000 + 364k, LENGTH = 2048k - 364k
+    RAM(rwx) : ORIGIN =  0x20000000, LENGTH = 256k
+    SCRATCH_X(rwx) : ORIGIN = 0x20040000, LENGTH = 4k
+    SCRATCH_Y(rwx) : ORIGIN = 0x20041000, LENGTH = 4k
+}
+
+ENTRY(_entry_point)
+
+SECTIONS
+{
+    .flash_begin : {
+        __flash_binary_start = .;
+    } > FLASH_APP
+
+    /* Insert boot3, which is the combined boot2 + boot3 */
+    .boot3 : {
+        KEEP (*(.boot3))
+    } > FLASH_BL
+
+    /*
+     * Name a section for the image header.
+     * The contents will get replaced post-build
+     */
+    .app_hdr : {
+	LONG(0xdeaddead)
+	LONG(0)
+	LONG(0xdeaddead)
+    } > FLASH_IMGHDR
+
+    .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)
+        *(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_APP
+
+    .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_APP
+
+    .ARM.extab :
+    {
+        *(.ARM.extab* .gnu.linkonce.armextab.*)
+    } > FLASH_APP
+
+    __exidx_start = .;
+    .ARM.exidx :
+    {
+        *(.ARM.exidx* .gnu.linkonce.armexidx.*)
+    } > FLASH_APP
+    __exidx_end = .;
+
+    /* Machine inspectable binary information */
+    . = ALIGN(4);
+    __binary_info_start = .;
+    .binary_info :
+    {
+        KEEP(*(.binary_info.keep.*))
+        *(.binary_info.*)
+    } > FLASH_APP
+    __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_APP
+
+    .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_APP
+    __scratch_x_source__ = LOADADDR(.scratch_x);
+
+    .scratch_y : {
+        __scratch_y_start__ = .;
+        *(.scratch_y.*)
+        . = ALIGN(4);
+        __scratch_y_end__ = .;
+    } > SCRATCH_Y AT > FLASH_APP
+    __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_APP
+
+    /* 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 */
+}
+

gen_imghdr.py

@@ -0,0 +1,59 @@
+#!/usr/bin/env python3
+# Derived from pad_checksum in the Pico SDK, which carries the following
+# LICENSE.txt:
+# Copyright 2020 (c) 2020 Raspberry Pi (Trading) Ltd.
+# 
+# Redistribution and use in source and binary forms, with or without modification, are permitted provided that the
+# following conditions are met:
+# 
+# 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following
+#    disclaimer.
+# 
+# 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following
+#    disclaimer in the documentation and/or other materials provided with the distribution.
+# 
+# 3. Neither the name of the copyright holder nor the names of its contributors may be used to endorse or promote products
+#    derived from this software without specific prior written permission.
+# 
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
+# INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+# DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+# SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+# WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+# THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+import argparse
+import binascii
+import struct
+import sys
+
+def any_int(x):
+    try:
+        return int(x, 0)
+    except:
+        raise argparse.ArgumentTypeError("expected an integer, not '{!r}'".format(x))
+
+parser = argparse.ArgumentParser()
+parser.add_argument("ifile", help="Input application binary (binary)")
+parser.add_argument("ofile", help="Output header file (binary)")
+parser.add_argument("-a", "--addr", help="Load address of the application image",
+                    type=any_int, default=0x10004000)
+args = parser.parse_args()
+
+try:
+    idata = open(args.ifile, "rb").read()
+except:
+    sys.exit("Could not open input file '{}'".format(args.ifile))
+
+vtor = args.addr
+size = len(idata)
+crc = binascii.crc32(idata)
+
+odata = vtor.to_bytes(4, byteorder='little') + size.to_bytes(4, byteorder='little') + crc.to_bytes(4, byteorder='little')
+
+try:
+    with open(args.ofile, "wb") as ofile:
+        ofile.write(odata)
+except:
+    sys.exit("Could not open output file '{}'".format(args.ofile))

mkasm.py

@@ -0,0 +1,53 @@
+#!/usr/bin/env python3
+# Derived from pad_checksum in the Pico SDK, which carries the following
+# LICENSE.txt:
+# Copyright 2020 (c) 2020 Raspberry Pi (Trading) Ltd.
+#
+# Redistribution and use in source and binary forms, with or without modification, are permitted provided that the
+# following conditions are met:
+#
+# 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following
+#    disclaimer.
+#
+# 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following
+#    disclaimer in the documentation and/or other materials provided with the distribution.
+#
+# 3. Neither the name of the copyright holder nor the names of its contributors may be used to endorse or promote products
+#    derived from this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
+# INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+# DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+# SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+# WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+# THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+import argparse
+import binascii
+import struct
+import sys
+
+parser = argparse.ArgumentParser()
+parser.add_argument("ifile", help="Input file (binary)")
+parser.add_argument("ofile", help="Output file (assembly)")
+args = parser.parse_args()
+
+try:
+    idata = open(args.ifile, "rb").read()
+except:
+    sys.exit("Could not open input file '{}'".format(args.ifile))
+
+odata = idata
+
+try:
+    with open(args.ofile, "w") as ofile:
+        ofile.write("// ASM-ified version of: {}\n\n".format(args.ifile))
+        ofile.write(".cpu cortex-m0plus\n")
+        ofile.write(".thumb\n\n")
+        ofile.write(".section .boot3, \"ax\"\n\n")
+        for offs in range(0, len(odata), 16):
+            chunk = odata[offs:min(offs + 16, len(odata))]
+            ofile.write(".byte {}\n".format(", ".join("0x{:02x}".format(b) for b in chunk)))
+except:
+    sys.exit("Could not open output file '{}'".format(args.ofile))

standalone.ld

@@ -0,0 +1,234 @@
+/* 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)
+*/
+
+/* Skip 364kB at the start of flash, that's where the bootloader is */
+MEMORY
+{
+    FLASH(rx) : ORIGIN = 0x10000000 + 364k, LENGTH = 2048k - 364k
+    RAM(rwx) : ORIGIN =  0x20000000, LENGTH = 256k
+    SCRATCH_X(rwx) : ORIGIN = 0x20040000, LENGTH = 4k
+    SCRATCH_Y(rwx) : ORIGIN = 0x20041000, LENGTH = 4k
+}
+
+ENTRY(_entry_point)
+
+SECTIONS
+{
+    .flash_begin : {
+        __flash_binary_start = .;
+    } > FLASH
+
+    /* boot2 would normally go here, but we don't want it */
+
+    .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)
+        *(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
+
+    .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
+
+    .ARM.extab :
+    {
+        *(.ARM.extab* .gnu.linkonce.armextab.*)
+    } > FLASH
+
+    __exidx_start = .;
+    .ARM.exidx :
+    {
+        *(.ARM.exidx* .gnu.linkonce.armexidx.*)
+    } > FLASH
+    __exidx_end = .;
+
+    /* Machine inspectable binary information */
+    . = ALIGN(4);
+    __binary_info_start = .;
+    .binary_info :
+    {
+        KEEP(*(.binary_info.keep.*))
+        *(.binary_info.*)
+    } > FLASH
+    __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
+
+    .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
+    __scratch_x_source__ = LOADADDR(.scratch_x);
+
+    .scratch_y : {
+        __scratch_y_start__ = .;
+        *(.scratch_y.*)
+        . = ALIGN(4);
+        __scratch_y_end__ = .;
+    } > SCRATCH_Y AT > FLASH
+    __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
+
+    /* 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 */
+}
+