opensbi.git/Makefile, branch v1.7

Makefile: Add flag for reprodubility compiler flags

2025-06-15T12:58:55Z

Provides mechanism to remove absolute paths from binaries using -ffile-prefix-map It will help distros (e.g. yocto based ones ) which want to ship the .elf files but need to scrub absolute paths in objects Reviewed-by: Anup Patel Signed-off-by: Khem Raj Link: https://lore.kernel.org/r/20250515025931.3383142-1-raj.khem@gmail.com Signed-off-by: Anup Patel

Makefile: Make $(LLVM) more flexible

2025-06-14T04:41:11Z

Introduce a way for developers to easily switch between LLVM versions with LLVM=/path/to/llvm/ and LLVM=-version. This is a useful addition to the existing LLVM=1 variable which will select the first clang and llvm binutils available on the path. Reviewed-by: Anup Patel Tested-by: Anup Patel Signed-off-by: Charlie Jenkins Link: https://lore.kernel.org/r/20250430-improve_llvm_building-v1-1-caae96cc6be6@rivosinc.com Signed-off-by: Anup Patel

Makefile: fix missing .debug_frame DWARF section for GCC

2025-05-15T13:22:38Z

When OpenSBI is built with a relatively new compiler (gcc-13 and greater) I observed that GDB is unable to produce proper backtraces and some variable values appear corrupted (even if the associated DWARF location descriptor is correct). Turns out that to properly work with debug information, debuggers often need to unwind the stack. They generally rely on Call Frame Information (CFI) records provided by the compiler to facilitate this task. Currently, the GCC compiler offers two mechanisms: - `.debug_frame` section (as described in the DWARF specification). - `.eh_frame` sections (as described in LSB documents). The latter (`.eh_frame`) supports stack unwinding at runtime, providing a framework for C++ exceptions or enabling backtrace generation using libraries like libunwind. However, the downside of this approach is that these sections should be part of loadable segments. The former (`.debug_frame`) is simply an ordinary debug section. Starting from GCC 13, Linux targets enable the `-fasynchronous-unwind-tables` and `-funwind-tables` flags by default. Relevant commit: https://github.com/gcc-mirror/gcc/commit/3cd08f7168 When these flags are active, the compiler generates `.eh_frame` sections instead of `.debug_frame`. Since OpenSBI is built using the **Linux toolchain**, this behavior applies to OpenSBI as well. The problem arises because the SBI build system uses `-Wl,--gc-sections`, which discards the `.eh_frame` section. Possible Fixes: 1. Enforce `.debug_frame` generation – Modify compiler flags to generate `.debug_frame` instead of `.eh_frame`. 2. Preserve `.eh_frame` in the linker script – Add `KEEP(*(.eh_frame))` to ensure the section is not discarded. I chose Option 1 because it avoids any runtime overhead. Signed-off-by: Parshintsev Anatoly Reviewed-by: Anup Patel Link: https://lore.kernel.org/r/20250421124729.36364-1-anatoly.parshintsev@syntacore.com Signed-off-by: Anup Patel

Makefile: Avoid repeated evaluation of shell commands

2025-04-13T16:19:14Z

Recursively expanded variables (defined with '=') are expanded at evaluation time. These version information variables are evaluated inside a recipe as part of GENFLAGS. As a result, the shell commands are executed separately for each compiler invocation. Convert the version information variables to be simply expanded, so the shell commands are executed only once, at Makefile evaluation time. This speeds up the build by as much as 75%. A separate check is needed to maintain the behavior of preferring the value of OPENSBI_BUILD_TIME_STAMP from the environment. Signed-off-by: Samuel Holland Reviewed-by: Xiang W Reviewed-by: Anup Patel Link: https://lore.kernel.org/r/20250313035755.3796610-1-samuel.holland@sifive.com Signed-off-by: Anup Patel

lib: sbi: Avoid GOT indirection for global symbol references

2025-03-24T11:30:59Z

OpenSBI is compiled with -fPIE, which generally implies dynamic linking. This causes the compiler to generate GOT references for global symbols in order to support runtime symbol interposition. However, OpenSBI does not actually perform dynamic linking, so the GOT indirection just adds unnecessary overhead. The GOT references can be avoided by declaring global symbols with hidden visibility, thus making them local to this dynamic object and non-interposable. GCC/Clang's -fvisibility parameter is insufficient for this purpose when referencing objects from other translation units; either __attribute__((visibility(...)) or the pragma is required. Use the pragma since it is easier to apply to every symbol. Additionally clean up the one GOT reference from inline assembly. With this change, a firmware linked with LLD does not contain either a GOT or a PLT, and a firmware linked with BFD ld contains only a GOT with a single (unreferenced, legacy) _GLOBAL_OFFSET_TABLE_ entry. Signed-off-by: Samuel Holland Reviewed-by: Anup Patel

Makefile: remove carry output if scripts/carray.sh fails

2024-12-15T07:00:47Z

If the script fails, we end up trying to build either an empty or damaged .c file. Just remove it and let gcc fail on non-existent file. Signed-off-by: Ben Dooks Reviewed-by: Anup Patel

Makefile: Don't enable V-extension using -march option

2024-12-15T06:00:48Z

Enabling V-extension using -march option causes OpenSBI boot-time hang with LLVM compiler. As a work-around, don't enable V-extension using -march option and instead use a custom OpenSBI specific define inform availability of V-extension to lib/sbi/sbi_trap_v_ldst.c. Fixes: c2acc5e5b0d8 ("lib: sbi_misaligned_ldst: Add handling of vector load/store") Signed-off-by: Anup Patel Reviewed-by: Samuel Holland

lib: sbi_misaligned_ldst: Add handling of vector load/store

2024-12-06T12:13:06Z

Add misaligned load/store handling for the vector extension to the sbi_misaligned_ldst library. This implementation is inspired from the misaligned_vec_ldst implementation in the riscv-pk project. Co-developed-by: Zong Li Signed-off-by: Zong Li Signed-off-by: Nylon Chen Reviewed-by: Andy Chiu Reviewed-by: Anup Patel

Makefile: Fix POSIX grep for multiple patterns

2024-12-01T07:02:18Z

grep -e "-mstrict-align\|-mno-unaligned-access" makes use of GNU grep's backslash-escaped alternation operator \| which is available in basic regular expression syntax (BRE) mode. However, in POSIX grep's BRE mode | is an ordinary character which, when backslash-escaped, matches itself. Therefore, the search pattern becomes a plain string '-mstrict-align|-mno-unaligned-access' which obviously never matches the expected error and CC_SUPPORT_STRICT_ALIGN is always set to y. When cross-compiling with LLVM on amd64-unknown-openbsd7.6 host for riscv64-unknown-elf target this results in a compilation error: clang: error: unsupported option '-mno-unaligned-access' for target 'riscv64-unknown-elf' Using multiple -e options for this case maintains consistent behaviour across different grep implementations and fixes the issue. Signed-off-by: Igor Melnikov Reviewed-by: Anup Patel

Makefile: enable --gc-sections

2024-11-06T10:59:39Z

The --gc-sections option enables the linker to perform garbage collection of unreferenced code and data, thereby reducing the binary size. The -ffunction-sections option will place each function into a separate section, so it is necessary to add .text.* to the linker script. Signed-off-by: Kele Zhang Signed-off-by: Yuan Tan Signed-off-by: Zhangjin Wu Reviewed-by: Bin Meng Reviewed-by: Xiang W Reviewed-by: Anup Patel