pico-sdk: Switch to picolibc #12
Conversation
| @@ -43,15 +43,16 @@ function(pico_define_boot_stage2 NAME SOURCES) | |||
| if (PICO_C_COMPILER_IS_CLANG) | |||
| target_link_options(${NAME} PRIVATE "-nostdlib") | |||
| elseif (PICO_C_COMPILER_IS_GNU) | |||
| target_link_options(${NAME} PRIVATE "--specs=nosys.specs") | |||
| target_compile_options(${NAME} PRIVATE "--specs=picolibc.specs") | |||
There was a problem hiding this comment.
Please add a history about this change to ChangeLog.zephyr.md.
This selects picolibc by using --specs=picolibc.specs for compiling and linking. The linker scripts are adjusted to add KEEP to ensure that --gc-sections doesn't remove the contents of the files. Signed-off-by: Keith Packard <keithp@keithp.com>
The boot loader can use picolibc even if the app needs newlib for some reason; we still get the picolibc benefits in the boot loader. |
| target_link_options(${NAME} PRIVATE "-nostartfiles") | ||
| endif () | ||
|
|
||
| # boot2_helpers include dir | ||
| target_include_directories(${NAME} PRIVATE ${PICO_BOOT_STAGE2_DIR}/asminclude) | ||
|
|
||
| target_link_libraries(${NAME} hardware_regs boot_stage2_headers) | ||
| target_link_options(${NAME} PRIVATE "LINKER:--script=${PICO_BOOT_STAGE2_DIR}/boot_stage2.ld") | ||
| target_link_options(${NAME} PRIVATE "-T${PICO_BOOT_STAGE2_DIR}/boot_stage2.ld") |
There was a problem hiding this comment.
It's a minor point, but I think long options are easier to read in scripts.
There was a problem hiding this comment.
picolibc's spec fragments only look for the -T version of this option, so we must use the short variant to prevent addition of the picolibc linker script here.
There was a problem hiding this comment.
OK, I got it.
Thank you for your clarification.
|
Could you take a look, please? |
Can you expand on this? What's the benefit? I've read the commit message and it has the what, but not the why of this. |
Probably the most visible benefit is a reduction in memory usage -- picolibc has smaller implementations of many core parts of the C library (stdio, ctype, locales) as well as general memory saving architectural changes (eliminating struct reent). It's also routinely tested for the target systems. I'll be enabling these tests within the Zephyr SDK build to catch bugs introduced in any part of the system (binutils, compiler, linker, libraries). Newlib lacks any visible CI system. |
|
Merged. Please update |
This selects picolibc by using --specs=picolibc.specs for compiling and linking. The linker scripts are adjusted to add KEEP to ensure that --gc-sections doesn't remove the contents of the files.