Thread (29 messages) 29 messages, 5 authors, 2023-12-18

Re: [PATCH 08/15] tracing: Introduce names for ring buffers

From: Steven Rostedt <rostedt@goodmis.org>
Date: 2023-12-13 00:16:25
Also in: kexec, linux-arm-kernel, linux-devicetree, linux-doc, linux-mm, lkml

On Wed, 13 Dec 2023 00:04:45 +0000
Alexander Graf [off-list ref] wrote:
With KHO (Kexec HandOver), we want to preserve trace buffers across
kexec. To carry over their state between kernels, the kernel needs a
common handle for them that exists on both sides. As handle we introduce
names for ring buffers. In a follow-up patch, the kernel can then use
these names to recover buffer contents for specific ring buffers.
Is there a way to use the trace_array name instead?

The trace_array is the structure that represents each tracing instance. And
it already has a name field. And if you can get the associated ring buffer
from that too.

struct trace_array *tr;

	tr->array_buffer.buffer

	tr->name

When you do: mkdir /sys/kernel/tracing/instance/foo

You create a new trace_array instance where tr->name = "foo" and allocates
the buffer for it as well.

-- Steve
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