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Date: Fri, 4 Sep 2026 17:43:09 +0100
From: Leo Yan <leo.yan@arm.com>
To: James Clark <james.clark@linaro.org>
Cc: John Garry <john.g.garry@oracle.com>, Will Deacon <will@kernel.org>,
	Mike Leach <mike.leach@arm.com>, Leo Yan <leo.yan@linux.dev>,
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	Suyash Mahar <smahar@meta.com>, Amir Ayupov <aaupov@fb.com>,
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	linux-arm-kernel@lists.infradead.org, coresight@lists.linaro.org,
	linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/6] perf: cs-etm: Don't add global v0 HW_IDs to
 unformatted queues
Message-ID: <20260904164309.GZ8904@e132581.arm.com>
References: <20260821-james-cs-hw_id-output-failure-v1-0-9d532ddabcc3@linaro.org>
 <20260821-james-cs-hw_id-output-failure-v1-1-9d532ddabcc3@linaro.org>
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In-Reply-To: <20260821-james-cs-hw_id-output-failure-v1-1-9d532ddabcc3@linaro.org>

On Fri, Aug 21, 2026 at 10:50:29AM +0100, James Clark wrote:
> In the case of mixed formatted and unformatted trace with v0 HW_IDs, or
> no HW_IDs at all resulting in the cs_etm__map_trace_ids_metadata()
> fallback, formatted queues will write their HW_IDs to unformatted
> queues.

I understand a session can support multiple sinks, but I don't expect
to mix up formatted and unformatted trace (see sinks_compatible()).

For the mentioned fallback, I am also struggling to establish a case.
Even AUX_OUTPUT_HW_ID records are absent randomly, I don't think this
impacts the queue's format initalization, no?