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Date:   Fri,  7 Aug 2020 12:50:29 +0100
From:   Alan Maguire <>
        Alan Maguire <>
Subject: [PATCH bpf] bpf: doc: remove references to warning message when using bpf_trace_printk()

The BPF helper bpf_trace_printk() no longer uses trace_printk();
it is now triggers a dedicated trace event.  Hence the described
warning is no longer present, so remove the discussion of it as
it may confuse people.

Fixes: ac5a72ea5c89 ("bpf: Use dedicated bpf_trace_printk event instead of trace_printk()")
Signed-off-by: Alan Maguire <>
 Documentation/bpf/bpf_design_QA.rst | 11 -----------
 1 file changed, 11 deletions(-)

diff --git a/Documentation/bpf/bpf_design_QA.rst b/Documentation/bpf/bpf_design_QA.rst
index 12a246f..2df7b06 100644
--- a/Documentation/bpf/bpf_design_QA.rst
+++ b/Documentation/bpf/bpf_design_QA.rst
@@ -246,17 +246,6 @@ program is loaded the kernel will print warning message, so
 this helper is only useful for experiments and prototypes.
 Tracing BPF programs are root only.
-Q: bpf_trace_printk() helper warning
-Q: When bpf_trace_printk() helper is used the kernel prints nasty
-warning message. Why is that?
-A: This is done to nudge program authors into better interfaces when
-programs need to pass data to user space. Like bpf_perf_event_output()
-can be used to efficiently stream data via perf ring buffer.
-BPF maps can be used for asynchronous data sharing between kernel
-and user space. bpf_trace_printk() should only be used for debugging.
 Q: New functionality via kernel modules?
 Q: Can BPF functionality such as new program or map types, new

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