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It prints a return value even when the traced function returns void. 2. When the return type is narrower than a register, the printed value may be incorrect because high bits can contain undefined data. Both issues are addressed by using BTF to obtain the precise return type of each traced function: - Return values are now printed only for functions whose return type is not void. - The value is truncated to the actual width of the return type, ensuring correct representation. These changes make the funcgraph-retval output more accurate and remove noise from void functions. pengdonglin (2): fgraph: use BTF to trim and filter return values tracing: Update funcgraph-retval documentation Documentation/trace/ftrace.rst | 74 +++++++++++++++------------- kernel/trace/trace_functions_graph.c | 64 ++++++++++++++++++++---- 2 files changed, 94 insertions(+), 44 deletions(-) -- 2.34.1