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Fix basic picolibc support #2898

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Merged
kilograham merged 4 commits into from
Apr 15, 2026
Merged

Fix basic picolibc support #2898

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cd3b296
Fix basic picolibc support
kilograham Apr 13, 2026
ad0fda9
update linker script comments
kilograham Apr 15, 2026
b6bd627
update comment
kilograham Apr 15, 2026
e7c45f7
update comment
kilograham Apr 15, 2026
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1 change: 1 addition & 0 deletions src/rp2040/boot_stage2/CMakeLists.txt
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Expand Up @@ -49,6 +49,7 @@ function(pico_define_boot_stage2 NAME SOURCES)
if (PICO_C_COMPILER_IS_CLANG)
target_link_options(${NAME} PRIVATE "-nostdlib")
elseif (PICO_C_COMPILER_IS_GNU)
# this disables newlib's implementation of syscalls such as _read
target_link_options(${NAME} PRIVATE "--specs=nosys.specs")
target_link_options(${NAME} PRIVATE "-nostartfiles")
endif ()
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1 change: 1 addition & 0 deletions src/rp2350/boot_stage2/CMakeLists.txt
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Expand Up @@ -49,6 +49,7 @@ function(pico_define_boot_stage2 NAME SOURCES)
if (PICO_C_COMPILER_IS_CLANG)
target_link_options(${NAME} PRIVATE "-nostdlib")
elseif (PICO_C_COMPILER_IS_GNU)
# this disables newlib's implementation of syscalls such as _read
target_link_options(${NAME} PRIVATE "--specs=nosys.specs")
target_link_options(${NAME} PRIVATE "-nostartfiles")
endif ()
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6 changes: 6 additions & 0 deletions src/rp2_common/pico_clib_interface/picolibc_interface.c
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Expand Up @@ -58,6 +58,12 @@ static FILE __stdio = FDEV_SETUP_STREAM(picolibc_putc,
picolibc_flush,
_FDEV_SETUP_RW);

#ifdef __GNUCLIKE_PRAGMA_DIAGNOSTIC
#pragma GCC diagnostic ignored "-Wpragmas"
#pragma GCC diagnostic ignored "-Wunknown-warning-option"
#pragma GCC diagnostic ignored "-Wredundant-decls"
#endif

FILE *const stdin = &__stdio; __strong_reference(stdin, stdout); __strong_reference(stdin, stderr);

void __weak __assert_func(const char *file, int line, const char *func, const char *failedexpr) {
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1 change: 1 addition & 0 deletions src/rp2_common/pico_cxx_options/new_delete.cpp
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Expand Up @@ -8,6 +8,7 @@
// Override the standard allocators to use regular malloc/free

#if !PICO_CXX_DISABLE_ALLOCATION_OVERRIDES // Let user override
#include <stdlib.h> // weird looking but it is required if dropping picolibc on top of GCC+newlib (reent issue)
#include <cstdlib>
#include "pico.h"

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3 changes: 3 additions & 0 deletions src/rp2_common/pico_platform_compiler/include/pico/platform/compiler.h
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Expand Up @@ -21,6 +21,9 @@

#if defined __GNUC__
#include <sys/cdefs.h>
#if !defined(__printflike) && defined(__picolibc_format)
#define __printflike(a,b) __picolibc_format(printf,a,b)
#endif
// note LLVM defines __GNUC__
#ifdef __clang__
#define PICO_C_COMPILER_IS_CLANG 1
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5 changes: 4 additions & 1 deletion src/rp2_common/pico_runtime/CMakeLists.txt
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Expand Up @@ -46,7 +46,10 @@ endforeach()

# todo is this correct/needed?
if (PICO_C_COMPILER_IS_GNU)
target_link_options(pico_runtime INTERFACE "--specs=nosys.specs")
if (PICO_LIBC STREQUAL "newlib")
# this disables newlib's implementation of syscalls such as _read
target_link_options(pico_runtime INTERFACE "--specs=nosys.specs")
endif()
elseif (PICO_C_COMPILER_IS_CLANG)
# target_link_options(pico_runtime INTERFACE "-nostdlib")
endif()
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3 changes: 2 additions & 1 deletion src/rp2_common/pico_standard_link/CMakeLists.txt
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Expand Up @@ -178,7 +178,8 @@ if (NOT TARGET pico_standard_link)
# if PICO_TARGET_BINARY_TYPE is set to foo on the target, otherwise ${CMAKE_CURRENT_LIST_DIR}/memmap_${PICO_DEFAULT_BINARY_TYPE).ld
set(_LINKER_SCRIPT_EXPRESSION "$<IF:$<BOOL:$<TARGET_PROPERTY:PICO_TARGET_LINKER_SCRIPT>>,$<TARGET_PROPERTY:PICO_TARGET_LINKER_SCRIPT>,${PICO_LINKER_SCRIPT_PATH}/memmap_$<IF:$<STREQUAL:$<TARGET_PROPERTY:PICO_TARGET_BINARY_TYPE>,>,${PICO_DEFAULT_BINARY_TYPE},$<TARGET_PROPERTY:PICO_TARGET_BINARY_TYPE>>.ld>")
target_link_options(pico_standard_link INTERFACE
"LINKER:--script=${_LINKER_SCRIPT_EXPRESSION}"
# use -T instead of --script here, as picolibc.specs looks for any -T not --linker to suppress injection of its own linker script
"-T${_LINKER_SCRIPT_EXPRESSION}"
)
pico_add_link_depend(pico_standard_link ${_LINKER_SCRIPT_EXPRESSION})
unset(_LINKER_SCRIPT_EXPRESSION)
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3 changes: 3 additions & 0 deletions src/rp2_common/pico_standard_link/script_include/section_copy_to_ram_data.incl
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Expand Up @@ -3,6 +3,7 @@
__mutex_array_start, __mutex_array_end
__preinit_array_start, __preinit_array_end
__init_array_start, __init_array_end
__bothinit_array_start, __bothinit_array_end
__fini_array_start, __fini_array_end
__tdata_end
__etext
Expand Down Expand Up @@ -35,6 +36,7 @@ SECTIONS

. = ALIGN(4);
/* preinit data */
PROVIDE_HIDDEN (__bothinit_array_start = .);
Comment thread
kilograham marked this conversation as resolved.
PROVIDE_HIDDEN (__preinit_array_start = .);
KEEP(*(SORT(.preinit_array.*)))
KEEP(*(.preinit_array))
Expand All @@ -46,6 +48,7 @@ SECTIONS
KEEP(*(SORT(.init_array.*)))
KEEP(*(.init_array))
PROVIDE_HIDDEN (__init_array_end = .);
PROVIDE_HIDDEN (__bothinit_array_end = .);

. = ALIGN(4);
/* finit data */
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3 changes: 3 additions & 0 deletions src/rp2_common/pico_standard_link/script_include/section_default_text.incl
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Expand Up @@ -4,6 +4,7 @@
__embedded_block_end
__preinit_array_start, __preinit_array_end
__init_array_start, __init_array_end
__bothinit_array_start, __bothinit_array_end
__fini_array_start, __fini_array_end
*/

Expand Down Expand Up @@ -51,6 +52,7 @@ SECTIONS

. = ALIGN(4);
/* preinit data */
PROVIDE_HIDDEN (__bothinit_array_start = .);
PROVIDE_HIDDEN (__preinit_array_start = .);
KEEP(*(SORT(.preinit_array.*)))
KEEP(*(.preinit_array))
Expand All @@ -62,6 +64,7 @@ SECTIONS
KEEP(*(SORT(.init_array.*)))
KEEP(*(.init_array))
PROVIDE_HIDDEN (__init_array_end = .);
PROVIDE_HIDDEN (__bothinit_array_end = .);

. = ALIGN(4);
/* finit data */
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3 changes: 3 additions & 0 deletions src/rp2_common/pico_standard_link/script_include/section_no_flash_data.incl
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Expand Up @@ -3,6 +3,7 @@
__mutex_array_start, __mutex_array_end
__preinit_array_start, __preinit_array_end
__init_array_start, __init_array_end
__bothinit_array_start, __bothinit_array_end
__fini_array_start, __fini_array_end
__tdata_end
__etext
Expand Down Expand Up @@ -30,6 +31,7 @@ SECTIONS

. = ALIGN(4);
/* preinit data */
PROVIDE_HIDDEN (__bothinit_array_start = .);
PROVIDE_HIDDEN (__preinit_array_start = .);
KEEP(*(SORT(.preinit_array.*)))
KEEP(*(.preinit_array))
Expand All @@ -41,6 +43,7 @@ SECTIONS
KEEP(*(SORT(.init_array.*)))
KEEP(*(.init_array))
PROVIDE_HIDDEN (__init_array_end = .);
PROVIDE_HIDDEN (__bothinit_array_end = .);

. = ALIGN(4);
/* finit data */
Expand Down
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