linux-kernel - Re: [PATCH v5 08/13] coresight: Interpret perf config with ATTR_CFG_GET

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Message-ID: <20251119123647.GC8204@e132581.arm.com>
Date: Wed, 19 Nov 2025 12:36:47 +0000
From: Leo Yan <leo.yan@....com>
To: James Clark <james.clark@...aro.org>
Cc: Mike Leach <mike.leach@...aro.org>,
	Suzuki K Poulose <suzuki.poulose@....com>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Jonathan Corbet <corbet@....net>,
	Randy Dunlap <rdunlap@...radead.org>, coresight@...ts.linaro.org,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	linux-doc@...r.kernel.org
Subject: Re: [PATCH v5 08/13] coresight: Interpret perf config with
 ATTR_CFG_GET_FLD()

On Wed, Nov 19, 2025 at 12:00:30PM +0000, James Clark wrote:

[...]

> ...  But then to make
> the code match the warning it might also make sense to change CONFIG_ARM64
> back to CONFIG_CORESIGHT_SOURCE_ETM4X, which Leo suggested to change. Maybe
> I can just delete the warning text, practically this warning can never be
> hit.

Armv8 CPUs can runs in aarch32 mode, strictly speaking, we should also
can run ETMv4 driver in aarch32 mode as well.  Then CONFIG_ARM64 is the
right choice, this can remind us that `is_kernel_in_hyp_mode()` is
always stick to aarch64 mode.

  static ssize_t format_attr_contextid_show(struct device *dev,
                                            struct device_attribute *attr,
                                            char *page)
  {
  #if IS_ENABLED(CONFIG_ARM64)
       if (is_kernel_in_hyp_mode())
               return contextid2_show(dev, attr, page);
  #endif

       return contextid1_show(dev, attr, page);
  }

Thanks,
Leo