Use include linker scripts

bazel/config/BUILD.bazel

@@ -217,10 +217,22 @@ string_flag(
     build_setting_default = "Debug",
 )
 
-# PICO_BAZEL_CONFIG: PICO_DEFAULT_LINKER_SCRIPT, [Bazel only] The library that provides a linker script to link into all binaries, default=//src/rp2_common/pico_crt0:default_linker_script, group=pico_standard_link
+# PICO_BAZEL_CONFIG: PICO_DEFAULT_BINARY_TYPE, The default binary type to use, type=string, default=default, group=build
+string_flag(
+    name = "PICO_DEFAULT_BINARY_TYPE",
+    build_setting_default = "default",
+    values = [
+        "default",
+        "no_flash",
+        "copy_to_ram",
+        "blocked_ram",
+    ],
+)
+
+# PICO_BAZEL_CONFIG: PICO_DEFAULT_LINKER_SCRIPT, [Bazel only] The library that provides a linker script to link into all binaries, default=//src/rp2_common/pico_standard_link:default_linker_script, group=pico_standard_link
 label_flag(
     name = "PICO_DEFAULT_LINKER_SCRIPT",
-    build_setting_default = "//src/rp2_common/pico_crt0:default_linker_script",
+    build_setting_default = "//src/rp2_common/pico_standard_link:default_linker_script",
 )
 
 # PICO_BAZEL_CONFIG: PICO_NO_TARGET_NAME, Don't define PICO_TARGET_NAME, type=bool, default=0, group=build

bazel/constraint/BUILD.bazel

@@ -273,3 +273,18 @@ config_setting(
     name = "pico_compilation_no_fastbuild_args_set",
     flag_values = {"//bazel/config:PICO_COMPILATION_NO_FASTBUILD_ARGS": "True"},
 )
+
+config_setting(
+    name = "pico_binary_type_no_flash",
+    flag_values = {"//bazel/config:PICO_DEFAULT_BINARY_TYPE": "no_flash"},
+)
+
+config_setting(
+    name = "pico_binary_type_copy_to_ram",
+    flag_values = {"//bazel/config:PICO_DEFAULT_BINARY_TYPE": "copy_to_ram"},
+)
+
+config_setting(
+    name = "pico_binary_type_blocked_ram",
+    flag_values = {"//bazel/config:PICO_DEFAULT_BINARY_TYPE": "blocked_ram"},
+)

bazel/util/pico_linker_scripts.bzl

@@ -0,0 +1,38 @@
+load("@bazel_tools//tools/cpp:toolchain_utils.bzl", "use_cpp_toolchain")
+
+def _linker_scripts_impl(ctx):
+    link_flags = []
+    for script in ctx.attr.include_scripts:
+        link_include_dir = script.label.package
+        if ctx.label.workspace_root:
+            link_include_dir = "/".join((ctx.label.workspace_root, link_include_dir))
+        link_flag = "-L" + str(link_include_dir)
+        if not (link_flag in link_flags):
+            link_flags.append(link_flag)
+
+    for script in ctx.files.link_scripts:
+        link_flags.append("-T" + str(script.path))
+
+    all_scripts = ctx.files.link_scripts + ctx.files.include_scripts
+
+    linking_inputs = cc_common.create_linker_input(
+        owner = ctx.label,
+        user_link_flags = depset(
+            direct = link_flags,
+        ),
+        additional_inputs = depset(direct = all_scripts),
+    )
+    return [
+        DefaultInfo(files = depset(direct = all_scripts)),
+        CcInfo(linking_context = cc_common.create_linking_context(linker_inputs = depset(direct = [linking_inputs]))),
+    ]
+
+linker_scripts = rule(
+    implementation = _linker_scripts_impl,
+    attrs = {
+        "link_scripts": attr.label_list(allow_files = [".ld"], doc = "List of scripts to explicitly link"),
+        "include_scripts": attr.label_list(allow_files = [".incl"], doc = "List of scripts to include"),
+    },
+    toolchains = use_cpp_toolchain(),
+    fragments = ["cpp"],
+)

bazel/util/transition.bzl

@@ -167,3 +167,33 @@ extra_copts_for_all_deps = declare_transtion(
         "//command_line_option:copt": "extra_copts",
     },
 )
+
+# This transition sets the binary type
+pico_set_binary_type = declare_transtion(
+    attrs = {
+        "binary_type": attr.string(),
+        # This could be shared, but we don't in order to make it clearer that
+        # a transition is in use.
+        "_allowlist_function_transition": attr.label(
+            default = "@bazel_tools//tools/allowlists/function_transition_allowlist",
+        ),
+    },
+    flag_overrides = {
+        "@pico-sdk//bazel/config:PICO_DEFAULT_BINARY_TYPE": "binary_type",
+    },
+)
+
+# This transition sets the binary type
+pico_set_linker_script = declare_transtion(
+    attrs = {
+        "linker_script": attr.string(),
+        # This could be shared, but we don't in order to make it clearer that
+        # a transition is in use.
+        "_allowlist_function_transition": attr.label(
+            default = "@bazel_tools//tools/allowlists/function_transition_allowlist",
+        ),
+    },
+    flag_overrides = {
+        "@pico-sdk//bazel/config:PICO_DEFAULT_LINKER_SCRIPT": "linker_script",
+    },
+)

src/common/pico_base_headers/BUILD.bazel

@@ -74,6 +74,11 @@ cc_library(
         "//bazel/constraint:rp2040": ["PICO_RP2040=1"],
         "//bazel/constraint:rp2350": ["PICO_RP2350=1"],
         "//conditions:default": [],
+    }) + select({
+        "//bazel/constraint:pico_binary_type_no_flash": ["PICO_NO_FLASH=1"],
+        "//bazel/constraint:pico_binary_type_copy_to_ram": ["PICO_COPY_TO_RAM=1"],
+        "//bazel/constraint:pico_binary_type_blocked_ram": ["PICO_USE_BLOCKED_RAM=1"],
+        "//conditions:default": [],
     }),
 )
 

src/rp2040/pico_platform/BUILD.bazel

@@ -54,3 +54,96 @@ cc_library(
         "//src/rp2_common/pico_standard_link",
     ],
 )
+
+load("//bazel/util:pico_linker_scripts.bzl", "linker_scripts")
+
+exports_files(
+    [
+        "memmap_blocked_ram.ld",
+        "memmap_copy_to_ram.ld",
+        "memmap_default.ld",
+        "memmap_no_flash.ld",
+    ],
+)
+
+linker_scripts(
+    name = "memmap_default",
+    link_scripts = ["memmap_default.ld"],
+)
+
+linker_scripts(
+    name = "memmap_blocked_ram",
+    link_scripts = ["memmap_blocked_ram.ld"],
+)
+
+linker_scripts(
+    name = "memmap_copy_to_ram",
+    link_scripts = ["memmap_copy_to_ram.ld"],
+)
+
+linker_scripts(
+    name = "memmap_no_flash",
+    link_scripts = ["memmap_no_flash.ld"],
+)
+
+cc_library(
+    name = "default_linker_script",
+    target_compatible_with = ["//bazel/constraint:rp2040"],
+    visibility = [
+        "//src/rp2_common/pico_standard_link:__pkg__",
+    ],
+    deps = [
+        "//src/rp2_common/pico_crt0:no_warn_rwx_flag",
+        "//src/rp2040/pico_platform/script_include:rp2040_linker_scripts",
+        "//src/rp2_common/pico_standard_link/script_include:rp2_linker_scripts",
+        "//src/rp2_common/pico_standard_link:default_flash_region",
+        "memmap_default",
+    ],
+)
+
+# PICO_BUILD_DEFINE: PICO_USE_BLOCKED_RAM, whether this is a 'blocked_ram' build, type=bool, default=0, but dependent on CMake options, group=pico_standard_link
+cc_library(
+    name = "blocked_ram_linker_script",
+    target_compatible_with = ["//bazel/constraint:rp2040"],
+    visibility = [
+        "//src/rp2_common/pico_standard_link:__pkg__",
+    ],
+    deps = [
+        "//src/rp2_common/pico_crt0:no_warn_rwx_flag",
+        "//src/rp2040/pico_platform/script_include:rp2040_linker_scripts",
+        "//src/rp2_common/pico_standard_link/script_include:rp2_linker_scripts",
+        "//src/rp2_common/pico_standard_link:default_flash_region",
+        "memmap_blocked_ram",
+    ],
+)
+
+# PICO_BUILD_DEFINE: PICO_COPY_TO_RAM, whether this is a 'copy_to_ram' build, type=bool, default=0, but dependent on CMake options, group=pico_standard_link
+cc_library(
+    name = "copy_to_ram_linker_script",
+    target_compatible_with = ["//bazel/constraint:rp2040"],
+    visibility = [
+        "//src/rp2_common/pico_standard_link:__pkg__",
+    ],
+    deps = [
+        "//src/rp2_common/pico_crt0:no_warn_rwx_flag",
+        "//src/rp2040/pico_platform/script_include:rp2040_linker_scripts",
+        "//src/rp2_common/pico_standard_link/script_include:rp2_linker_scripts",
+        "//src/rp2_common/pico_standard_link:default_flash_region",
+        "memmap_copy_to_ram",
+    ],
+)
+
+# PICO_BUILD_DEFINE: PICO_NO_FLASH, whether this is a 'no_flash' build, type=bool, default=0, but dependent on CMake options, group=pico_standard_link
+cc_library(
+    name = "no_flash_linker_script",
+    target_compatible_with = ["//bazel/constraint:rp2040"],
+    visibility = [
+        "//src/rp2_common/pico_standard_link:__pkg__",
+    ],
+    deps = [
+        "//src/rp2_common/pico_crt0:no_warn_rwx_flag",
+        "//src/rp2040/pico_platform/script_include:rp2040_linker_scripts",
+        "//src/rp2_common/pico_standard_link/script_include:rp2_linker_scripts",
+        "memmap_no_flash",
+    ],
+)

src/rp2040/pico_platform/CMakeLists.txt

@@ -22,6 +22,21 @@ if (NOT TARGET pico_platform)
             pico_platform_panic
             pico_platform_sections
     )
+
+    pico_register_common_scope_var(PICO_LINKER_SCRIPT_PATH)
+    if (NOT PICO_LINKER_SCRIPT_PATH)
+        set(PICO_LINKER_SCRIPT_PATH ${CMAKE_CURRENT_LIST_DIR})
+    endif()
+
+    pico_register_common_scope_var(PICO_LINKER_DEFAULT_LOCATIONS_PATH)
+    if (NOT PICO_LINKER_DEFAULT_LOCATIONS_PATH)
+        set(PICO_LINKER_DEFAULT_LOCATIONS_PATH ${CMAKE_CURRENT_LIST_DIR}/script_include/default_locations.ld)
+    endif()
+
+    pico_register_common_scope_var(PICO_LINKER_SCRIPT_INCLUDE_DIRS)
+    list(APPEND PICO_LINKER_SCRIPT_INCLUDE_DIRS ${CMAKE_CURRENT_LIST_DIR}/script_include)
+
+    pico_promote_common_scope_vars()
 endif()
 
 function(pico_add_platform_library TARGET)

src/rp2040/pico_platform/memmap_blocked_ram.ld

@@ -0,0 +1,4 @@
+/* Use blocked ram */
+RAM_ORIGIN = 0x21000000;
+
+INCLUDE "memmap_default.incl"

src/rp2040/pico_platform/memmap_copy_to_ram.ld

@@ -0,0 +1 @@
+INCLUDE "memmap_copy_to_ram.incl"

src/rp2040/pico_platform/memmap_default.ld

@@ -0,0 +1 @@
+INCLUDE "memmap_default.incl"

src/rp2040/pico_platform/memmap_no_flash.ld

@@ -0,0 +1 @@
+INCLUDE "memmap_no_flash.incl"

src/rp2040/pico_platform/script_include/BUILD.bazel

@@ -0,0 +1,19 @@
+load("@rules_cc//cc:cc_library.bzl", "cc_library")
+
+package(default_visibility = ["//visibility:public"])
+
+load("//bazel/util:pico_linker_scripts.bzl", "linker_scripts")
+
+linker_scripts(
+    name = "rp2040_linker_script_includes",
+    link_scripts = ["default_locations.ld"],
+    include_scripts = glob(["*.incl"]),
+)
+
+cc_library(
+    name = "rp2040_linker_scripts",
+    target_compatible_with = ["//bazel/constraint:rp2040"],
+    deps = [
+        "rp2040_linker_script_includes",
+    ],
+)

src/rp2040/pico_platform/script_include/default_locations.ld

@@ -0,0 +1,8 @@
+RAM_ORIGIN_DEFAULT = 0x20000000;
+RAM_LENGTH_DEFAULT = 256k;
+SCRATCH_X_ORIGIN_DEFAULT = 0x20040000;
+SCRATCH_X_LENGTH_DEFAULT = 4k;
+SCRATCH_Y_ORIGIN_DEFAULT = 0x20041000;
+SCRATCH_Y_LENGTH_DEFAULT = 4k;
+XIP_RAM_ORIGIN_DEFAULT = 0x15000000;
+XIP_RAM_LENGTH_DEFAULT = 16k;

src/rp2040/pico_platform/script_include/section_boot2.incl

@@ -0,0 +1,16 @@
+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
+    */
+
+    .boot2 : {
+        __boot2_start__ = .;
+        KEEP (*(.boot2))
+        __boot2_end__ = .;
+    } > TEXT_STORE
+
+    ASSERT(__boot2_end__ - __boot2_start__ == 256,
+        "ERROR: Pico second stage bootloader must be exactly 256 bytes in size for RP2040")
+}

src/rp2040/pico_platform/script_include/section_no_flash_text.incl

@@ -0,0 +1,47 @@
+/* Defines the following symbols for use by code:
+    __logical_binary_start
+    __binary_info_header_end
+    __embedded_block_end
+    __reset_start, __reset_end
+*/
+
+SECTIONS
+{
+    /* Note in NO_FLASH builds the entry point for both the bootrom, and debugger
+       entry (ELF entry point), are *first* in the image, and the vector table
+       follows immediately afterward. This is because the bootrom enters RAM
+       binaries directly at their lowest address (preferring main RAM over XIP
+       cache-as-SRAM if both are used).
+    */
+
+    .text : {
+        __logical_binary_start = .;
+        __reset_start = .;
+        KEEP (*(.reset))
+        __reset_end = .;
+        KEEP (*(.binary_info_header))
+        __binary_info_header_end = .;
+        KEEP (*(.embedded_block))
+        __embedded_block_end = .;
+        . = ALIGN(256);
+        KEEP (*(.vectors))
+        *(.text*)
+        . = ALIGN(4);
+        *(.init)
+        *(.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*)
+    } > RAM
+}

src/rp2040/pico_platform/script_include/section_platform_end.incl

@@ -0,0 +1,4 @@
+SECTIONS
+{
+    ASSERT( __binary_info_header_end - __logical_binary_start <= 256, "Binary info must be in first 256 bytes of the binary")
+}

src/rp2040/pico_platform/script_include/sections_copy_to_ram_text.incl

@@ -0,0 +1,11 @@
+/* This swaps section_boot2 and section_default_text, because RP2040 binaries must begin with boot2 */
+
+INCLUDE "section_flash_begin.incl"
+INCLUDE "section_boot2.incl"
+INCLUDE "section_copy_to_ram_flashtext.incl"
+INCLUDE "section_copy_to_ram_rodata.incl"
+INCLUDE "sections_arm_ex.incl"
+INCLUDE "section_binary_info.incl"
+INCLUDE "section_ram_vector_table.incl"
+INCLUDE "section_uninitialized_data.incl"
+INCLUDE "section_copy_to_ram_text.incl"

src/rp2040/pico_platform/script_include/sections_default_text.incl

@@ -0,0 +1,8 @@
+/* This swaps section_boot2 and section_default_text, because RP2040 binaries must begin with boot2 */
+
+INCLUDE "section_flash_begin.incl"
+INCLUDE "section_boot2.incl"
+INCLUDE "section_default_text.incl"
+INCLUDE "section_default_rodata.incl"
+INCLUDE "sections_arm_ex.incl"
+INCLUDE "section_binary_info.incl"