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authorRob Herring (Arm) <robh@kernel.org>2026-08-31 14:43:51 -0500
committerDmitry Torokhov <dmitry.torokhov@gmail.com>2026-09-13 18:17:31 -0700
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Input: tsc2007 - read "ti,poll-period" as u32grafted
The "ti,poll-period" property is documented as a normal uint32 cell. The driver used a u64 helper, which makes the helper type disagree with the schema even though the stored value is still small. Read "ti,poll-period" with the u32 helper matching the documented DT cell size. Assisted-by: Codex:gpt-5-5 Signed-off-by: Rob Herring (Arm) <robh@kernel.org> Link: https://patch.msgid.link/20260831194352.1185860-1-robh@kernel.org Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
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+.. SPDX-License-Identifier: GPL-2.0
+
+===============
+Tracing Remotes
+===============
+
+:Author: Vincent Donnefort <vdonnefort@google.com>
+
+Overview
+========
+Firmware and hypervisors are black boxes to the kernel. Having a way to see what
+they are doing can be useful to debug both. This is where remote tracing buffers
+come in. A remote tracing buffer is a ring buffer executed by the firmware or
+hypervisor into memory that is memory mapped to the host kernel. This is similar
+to how user space memory maps the kernel ring buffer but in this case the kernel
+is acting like user space and the firmware or hypervisor is the "kernel" side.
+With a trace remote ring buffer, the firmware and hypervisor can record events
+for which the host kernel can see and expose to user space.
+
+Register a remote
+=================
+A remote must provide a set of callbacks `struct trace_remote_callbacks` whom
+description can be found below. Those callbacks allows Tracefs to enable and
+disable tracing and events, to load and unload a tracing buffer (a set of
+ring-buffers) and to swap a reader page with the head page, which enables
+consuming reading.
+
+.. kernel-doc:: include/linux/trace_remote.h
+
+Once registered, an instance will appear for this remote in the Tracefs
+directory **remotes/**. Buffers can then be read using the usual Tracefs files
+**trace_pipe** and **trace**.
+
+Declare a remote event
+======================
+Macros are provided to ease the declaration of remote events, in a similar
+fashion to in-kernel events. A declaration must provide an ID, a description of
+the event arguments and how to print the event:
+
+.. code-block:: c
+
+ REMOTE_EVENT(foo, EVENT_FOO_ID,
+ RE_STRUCT(
+ re_field(u64, bar)
+ ),
+ RE_PRINTK("bar=%lld", __entry->bar)
+ );
+
+Then those events must be declared in a C file with the following:
+
+.. code-block:: c
+
+ #define REMOTE_EVENT_INCLUDE_FILE foo_events.h
+ #include <trace/define_remote_events.h>
+
+This will provide a `struct remote_event remote_event_foo` that can be given to
+`trace_remote_register`.
+
+Registered events appear in the remote directory under **events/**.
+
+Simple ring-buffer
+==================
+A simple implementation for a ring-buffer writer can be found in
+kernel/trace/simple_ring_buffer.c.
+
+.. kernel-doc:: include/linux/simple_ring_buffer.h