[ATfE] Cherrypick libc fixes for ATfE 22 release#693
Merged
voltur01 merged 5 commits intoarm:release/arm-software/22.xfrom Jan 22, 2026
Merged
[ATfE] Cherrypick libc fixes for ATfE 22 release#693voltur01 merged 5 commits intoarm:release/arm-software/22.xfrom
voltur01 merged 5 commits intoarm:release/arm-software/22.xfrom
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Semihosting SYS_READ call on stdin just returns immediately indicating no data was read, thus rendering stdin unusable with QEMU. SYS_READC blocks and waits for one symbol to be read from the terminal, however Enter key specifically is returned as '\r', thus the special case (that may not generalize well beyond QEMU). (cherry picked from commit b407fd6)
After llvm/llvm-project#174967 RUNTIMES_USE_LIBC=llvm-libc option provides all necessary defines for libcxx to work with LLVM libc. (cherry picked from commit 227f790)
…de (arm#678) LLVM libc does not provide a way to redefine abort(), thus the local abort() definition in LLVM libc semihosting has to be removed. Calls to abort() in LLVM libc crt0 replaced with __llvm_libc_exit() which is the LLVM libc defined platform specific exit handler. This prevents exception handlers from crashing because of the trap instruction in LLVM libc implementation of abort(). (cherry picked from commit 6859f67)
This removes the TODO comment to implement cleanup like calling cxa_finalize. It was confirmed and captured in the updated comment that this is already done by LLVM libc's exit() implementation. (cherry picked from commit 3872774)
Provide init and exit handlers for not hosted environments in llvm libc crt0. Update the documentation accordingly. Update the UART sample to make use of the symbols provided in crt0 and refine the comments for the remaining symbols related to IO retargeting. (cherry picked from commit ab657ec)
dcandler
approved these changes
Jan 22, 2026
HugoSilvaSantos
approved these changes
Jan 22, 2026
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This applies the following changes to 22.x release branch:
#667
[ATfE] Use semihosting SYS_READC for stdin with llvm libc
#676
[ATfE] Remove LLVM_LIBC define workaround for libcxx
#678
[ATfE] Replace call to abort with __llvm_libc_exit in libc startup code
#679
[ATfE] Update comment about handling cleanup for exit()
#683
[ATfE] Provide nohost init and exit in llvmlibc startup code