[SRU][N][PATCH 0/3] Coresight fails to build on 6.8.0-102 due to missing function and arg definitions

Mon Feb 23 14:05:12 UTC 2026

On 21/02/2026 02:01, Noah Wager wrote:
> BugLink: https://bugs.launchpad.net/bugs/2142337
> 
> SRU Justification:
> 
> [Impact]
> 
> When CONFIG_CORESIGHT is enabled, noble 6.8.0-102 fails to build with the following errors:
> 
> ```
> drivers/hwtracing/coresight/coresight-catu.c: In function 'catu_init':
> drivers/hwtracing/coresight/coresight-catu.c:728:15: error: implicit declaration of function 'coresight_init_driver' [-Werror=implicit-function-declaration]
>    728 | ret = coresight_init_driver("catu", &catu_driver, &catu_platform_driver);
>        | ^~~~~~~~~~~~~~~~~~~~~
> drivers/hwtracing/coresight/coresight-catu.c: In function 'catu_exit':
> drivers/hwtracing/coresight/coresight-catu.c:736:9: error: implicit declaration of function 'coresight_remove_driver'; did you mean 'coresight_remove_links'? [-Werror=implicit-function-declaration]
>    736 | coresight_remove_driver(&catu_driver, &catu_platform_driver);
>        | ^~~~~~~~~~~~~~~~~~~~~~~
>        | coresight_remove_links
> drivers/hwtracing/coresight/coresight-tmc-core.c: In function '__tmc_probe':
> drivers/hwtracing/coresight/coresight-tmc-core.c:500:65: error: 'id' undeclared (first use in this function); did you mean 'fd'?
>    500 | coresight_get_uci_data(id));
>        | ^~
>        | fd
> drivers/hwtracing/coresight/coresight-tmc-core.c:500:65: note: each undeclared identifier is reported only once for each function it appears in
> drivers/hwtracing/coresight/coresight-tmc-core.c: In function 'tmc_init':
> drivers/hwtracing/coresight/coresight-tmc-core.c:728:16: error: implicit declaration of function 'coresight_init_driver' [-Werror=implicit-function-declaration]
>    728 | return coresight_init_driver("tmc", &tmc_driver, &tmc_platform_driver);
>        | ^~~~~~~~~~~~~~~~~~~~~
> drivers/hwtracing/coresight/coresight-tmc-core.c: In function 'tmc_exit':
> drivers/hwtracing/coresight/coresight-tmc-core.c:733:9: error: implicit declaration of function 'coresight_remove_driver'; did you mean 'coresight_remove_links'? [-Werror=implicit-function-declaration]
>    733 | coresight_remove_driver(&tmc_driver, &tmc_platform_driver);
>        | ^~~~~~~~~~~~~~~~~~~~~~~
>        | coresight_remove_links
> ```
> 
> These errors are a result of including the following patches in upstream stable updates, but missing some dependencies from the original patch sets:
> 
>    Error description: __tmc_probe:id not defined
>    Break commit: n/linux aaf260b9572e ("coresight: tmc: Move ACPI support from AMBA driver to platform driver")
>    Missing commit: 852e9a32058a ("coresight: stm: Extract device name from AMBA pid based table lookup")
>                    3ab210297c31 ("coresight: tmc: Extract device properties from AMBA pid based table lookup")
>    Patch series: "coresight: Move remaining AMBA ACPI devices into platform driver"
>                  (https://lists-ec2.linaro.org/archives/list/coresight@lists.linaro.org/thread/XGJAJMHSDE5P7YSX33CIW5DHKR6C343L/)
> 
>    Error description: coresight_{init,remove}_driver not defined
>    Break commit: n/linux aaf260b9572e ("coresight: tmc: Move ACPI support from AMBA driver to platform driver")
>    Missing commit: 075b7cd7ad7d ("coresight: Add helpers registering/removing both AMBA and platform drivers")
>    Patch series: "coresight: Move remaining AMBA ACPI devices into platform driver"
>                  (https://lists-ec2.linaro.org/archives/list/coresight@lists.linaro.org/thread/XGJAJMHSDE5P7YSX33CIW5DHKR6C343L/)
> 
> [Fix]
> 
> Cherry-pick upstream commits:
> 852e9a32058a ("coresight: stm: Extract device name from AMBA pid based table lookup")
> 3ab210297c31 ("coresight: tmc: Extract device properties from AMBA pid based table lookup")
> 075b7cd7ad7d ("coresight: Add helpers registering/removing both AMBA and platform drivers")
> from the series:
> "coresight: Move remaining AMBA ACPI devices into platform driver".
> 
> NOTE: The series also has "Move remaining AMBA ACPI devices into platform driver"
> commits for the remaining devices, but I elected not to port them. We have
> the respective commits for tmc and catu applied because they were
> dependencies of "{tmc,catu}: Support atclk", but since the commits for the
> other devices are not necessary for the patches to apply, and as of now there
> are no upstream stable candidates with "Fixes" for the other devices, I don't
> think it's worth the increased change size. Fortunately, if they are needed
> in the future, they are clean cherry-picks (besides simple context changes)
> and we have all the dependencies.

Hm, though this is minimal I wonder whether it would be another case of 
deciding whether the change that broke the build was one that is really 
required in 6.8. This driver seems to have seen a lot of rework since 
6.8 and 6.12. Which poses quite a bit of chances that anything coming 
via 6.12.y is because it got broken after 6.8...

-Stefan

> 
> [Test Plan]
> 
> Ensure CONFIG_CORESIGHT and CONFIG_CORESIGHT_CATU are enabled, then compile test.
> 
> [Where problems could occur]
> 
> There is a low chance of regression because these commits are only small
> refactors that don't change behaviour. Only static function definitions are
> modified, and functionality is only added via new helpers, not removed.
> The new patches have a potential to create conflicts for derivative kernels
> and other downstream projects that rebase on this kernel.
> 
> Anshuman Khandual (3):
>    coresight: stm: Extract device name from AMBA pid based table lookup
>    coresight: tmc: Extract device properties from AMBA pid based table
>      lookup
>    coresight: Add helpers registering/removing both AMBA and platform
>      drivers
> 
>   drivers/hwtracing/coresight/coresight-core.c  | 29 +++++++++++++++++++
>   .../hwtracing/coresight/coresight-funnel.c    | 19 ++----------
>   drivers/hwtracing/coresight/coresight-priv.h  | 10 +++++++
>   .../coresight/coresight-replicator.c          | 20 ++-----------
>   drivers/hwtracing/coresight/coresight-stm.c   | 12 +++++++-
>   .../hwtracing/coresight/coresight-tmc-core.c  | 14 ++++++---
>   include/linux/coresight.h                     |  7 +++++
>   7 files changed, 72 insertions(+), 39 deletions(-)
> 

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