user/sven/linux.git/kernel/trace/trace_remote.c, branch next/HEAD

tracing: Non-consuming read for trace remotes with an offline CPU

2026-04-02T13:16:09Z

When a trace_buffer is created while a CPU is offline, this CPU is cleared from the trace_buffer CPU mask, preventing the creation of a non-consuming iterator (ring_buffer_iter). For trace remotes, it means the iterator fails to be allocated (-ENOMEM) even though there are available ring buffers in the trace_buffer. For non-consuming reads of trace remotes, skip missing ring_buffer_iter to allow reading the available ring buffers. Acked-by: Steven Rostedt (Google) Signed-off-by: Vincent Donnefort Link: https://patch.msgid.link/20260401045100.3394299-2-vdonnefort@google.com Signed-off-by: Marc Zyngier

tracing: Add events/ root files to trace remotes

2026-03-09T16:33:54Z

Just like for the kernel events directory, add 'enable', 'header_page' and 'header_event' at the root of the trace remote events/ directory. Link: https://patch.msgid.link/20260309162516.2623589-11-vdonnefort@google.com Reviewed-by: Steven Rostedt (Google) Signed-off-by: Vincent Donnefort Signed-off-by: Steven Rostedt (Google)

tracing: Add events to trace remotes

2026-03-09T16:33:54Z

An event is predefined point in the writer code that allows to log data. Following the same scheme as kernel events, add remote events, described to user-space within the events/ tracefs directory found in the corresponding trace remote. Remote events are expected to be described during the trace remote registration. Add also a .enable_event callback for trace_remote to toggle the event logging, if supported. Link: https://patch.msgid.link/20260309162516.2623589-10-vdonnefort@google.com Reviewed-by: Steven Rostedt (Google) Signed-off-by: Vincent Donnefort Signed-off-by: Steven Rostedt (Google)

tracing: Add init callback to trace remotes

2026-03-09T16:33:54Z

Add a .init call back so the trace remote callers can add entries to the tracefs directory. Link: https://patch.msgid.link/20260309162516.2623589-9-vdonnefort@google.com Reviewed-by: Steven Rostedt (Google) Signed-off-by: Vincent Donnefort Signed-off-by: Steven Rostedt (Google)

tracing: Add non-consuming read to trace remotes

2026-03-09T16:33:54Z

Allow reading the trace file for trace remotes. This performs a non-consuming read of the trace buffer. Link: https://patch.msgid.link/20260309162516.2623589-8-vdonnefort@google.com Reviewed-by: Steven Rostedt (Google) Signed-off-by: Vincent Donnefort Signed-off-by: Steven Rostedt (Google)

tracing: Add reset to trace remotes

2026-03-09T16:33:54Z

Allow to reset the trace remote buffer by writing to the Tracefs "trace" file. This is similar to the regular Tracefs interface. Link: https://patch.msgid.link/20260309162516.2623589-7-vdonnefort@google.com Reviewed-by: Steven Rostedt (Google) Signed-off-by: Vincent Donnefort Signed-off-by: Steven Rostedt (Google)

tracing: Introduce trace remotes

2026-03-09T16:33:53Z

A trace remote relies on ring-buffer remotes to read and control compatible tracing buffers, written by entity such as firmware or hypervisor. Add a Tracefs directory remotes/ that contains all instances of trace remotes. Each instance follows the same hierarchy as any other to ease the support by existing user-space tools. This currently does not provide any event support, which will come later. Link: https://patch.msgid.link/20260309162516.2623589-6-vdonnefort@google.com Reviewed-by: Steven Rostedt (Google) Signed-off-by: Vincent Donnefort Signed-off-by: Steven Rostedt (Google)