Re: [REGRESSION] drm/amd/display: amdgpu_dm_plane_test.ko fails to build due to modpost "too long symbol"

[Alex Hung <alex.hung@amd.com>]

On 7/10/26 02:52, Venkat Rao Bagalkote wrote:
> 
> On 10/07/26 1:31 pm, Venkat Rao Bagalkote wrote:
>>
>> On 10/07/26 10:45 am, Venkat Rao Bagalkote wrote:
>>>
>>> On 09/07/26 11:53 pm, Randy Dunlap wrote:
>>>>
>>>> On 7/7/26 10:05 PM, Venkat Rao Bagalkote wrote:
>>>>> Greetings!!!
>>>>>
>>>>> linux-next is failing to build for me with:
>>>>>
>>>>> ERROR: modpost: too long symbol
>>>>> "amdgpu_dm_plane_fill_gfx9_plane_attributes_from_modifiers"
>>>>> [drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/tests/ 
>>>>> amdgpu_dm_plane_test.ko]
>>>>>
>>>>> make[2]: *** [scripts/Makefile.modpost:147: Module.symvers] Error 1
>>>>> make[1]: *** [Makefile:2165: modpost] Error 2
>>>>> make: *** [Makefile:248: __sub-make] Error 2
>>>>>
>>>>> The failure occurs during modpost while building:
>>>>>
>>>>> drivers/gpu/drm/amd/display/amdgpu_dm/tests/amdgpu_dm_plane_test.ko
>>>>>
>>>>> This appears to be a regression in the AMD display KUnit test code.
>>>>>
>>>>> Could someone please take a look?
>>>>>
>>>>>
>>>>> If you happen to fix this, please add below tag.
>>>>>
>>>>> Reported-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
>>>> Hi,
>>>> I cannot reproduce this when using gcc v15.3.0.
>>>>
>>>> Which compiler & version are you using?
>>>>
>>> Hello,
>>>
>>> I am seeing this across below mentioned gcc version.
>>>
>>>
>>> gcc (GCC) 14.3.1 20251022 (Red Hat 14.3.1-4)
>>> gcc (GCC) 11.5.0 20240719 (Red Hat 11.5.0-11)
>>> gcc (GCC) 12.2.1 20221121 (Red Hat 12.2.1-7)
>>>
>>>
>>> Attched is the .config file.
>>
>> Git bisect is pointing to below commit as first bad commit.
>>
>>
>> # git bisect bad
>> 2b147895be109e0860269a7a72c697cdf049a885 is the first bad commit
>> commit 2b147895be109e0860269a7a72c697cdf049a885 (HEAD)
>> Author: Bhawanpreet Lakha <bhawanpreet.lakha@amd.com>
>> Date:   Fri Jun 12 16:12:21 2026 -0400
>>
>>     drm/amd/display: Add kunit tests for amdgpu_dm_plane
>>
>>     Add kunit tests for some functions in amdgpu_dm_plane.
>>
>>     Assisted-by: Copilot:Claude-Opus-4.8
>>     Reviewed-by: Alex Hung <alex.hung@amd.com>
>>     Signed-off-by: Bhawanpreet Lakha <bhawanpreet.lakha@amd.com>
>>     Signed-off-by: George Zhang <george.zhang@amd.com>
>>     Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
>>
>>  drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_plane.c   |  115 ++++ 
>> ++-----
>>  drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_plane.h   |   51 +++++
>>  drivers/gpu/drm/amd/display/amdgpu_dm/tests/Makefile  |    2 +
>>  drivers/gpu/drm/amd/display/amdgpu_dm/tests/amdgpu_dm_plane_test.c | 
>> 1204 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 
>> ++++++++++++++++++++++++++++++++++++++++++++++++
>>  4 files changed, 1325 insertions(+), 47 deletions(-)
>>  create mode 100644 drivers/gpu/drm/amd/display/amdgpu_dm/tests/ 
>> amdgpu_dm_plane_test.c
>>
> 
> 
> Hi,
> 
> I bisected this build failure and found that it is caused by the exported
> KUnit symbols:
> 
>    amdgpu_dm_plane_fill_gfx9_plane_attributes_from_modifiers()
>    amdgpu_dm_plane_fill_gfx12_plane_attributes_from_modifiers()
> 
> modpost rejects the resulting exported symbol name with:
> 
>    ERROR: modpost: too long symbol
>    "amdgpu_dm_plane_fill_gfx9_plane_attributes_from_modifiers"
> 
> I tested the following approach locally, which simply shortens the helper
> names to:
> 
>    amdgpu_dm_plane_fill_gfx9_attrs_from_modifiers()
>    amdgpu_dm_plane_fill_gfx12_attrs_from_modifiers()
> 
> and updated all corresponding users and KUnit references. This resolves the
> build issue for me and does not appear to introduce any functional changes.
> 
> Does this look like an acceptable fix?
> 
> If so, I'll prepare and send a formal patch with proper changelog.

This looks to me. Thanks for catching this.

> 
> 
> 
> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_plane.c b/ 
> drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_plane.c
> index 1b564cfe2120..b58225338bc4 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_plane.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_plane.c
> @@ -328,7 +328,7 @@ STATIC_IFN_KUNIT int 
> amdgpu_dm_plane_validate_dcc(struct amdgpu_device *adev,
>   }
>   EXPORT_IF_KUNIT(amdgpu_dm_plane_validate_dcc);
> 
> -STATIC_IFN_KUNIT int 
> amdgpu_dm_plane_fill_gfx9_plane_attributes_from_modifiers(struct 
> amdgpu_device *adev,
> +STATIC_IFN_KUNIT int 
> amdgpu_dm_plane_fill_gfx9_attrs_from_modifiers(struct amdgpu_device *adev,
>               const struct amdgpu_framebuffer *afb,
>               const enum surface_pixel_format format,
>               const enum dc_rotation_angle rotation,
> @@ -378,9 +378,9 @@ STATIC_IFN_KUNIT int 
> amdgpu_dm_plane_fill_gfx9_plane_attributes_from_modifiers(s
> 
>          return ret;
>   }
> - 
> EXPORT_IF_KUNIT(amdgpu_dm_plane_fill_gfx9_plane_attributes_from_modifiers);
> +EXPORT_IF_KUNIT(amdgpu_dm_plane_fill_gfx9_attrs_from_modifiers);
> 
> -STATIC_IFN_KUNIT int 
> amdgpu_dm_plane_fill_gfx12_plane_attributes_from_modifiers(struct 
> amdgpu_device *adev,
> +STATIC_IFN_KUNIT int 
> amdgpu_dm_plane_fill_gfx12_attrs_from_modifiers(struct amdgpu_device *adev,
>                const struct amdgpu_framebuffer *afb,
>                const enum surface_pixel_format format,
>                const enum dc_rotation_angle rotation,
> @@ -419,7 +419,7 @@ STATIC_IFN_KUNIT int 
> amdgpu_dm_plane_fill_gfx12_plane_attributes_from_modifiers(
> 
>          return ret;
>   }
> - 
> EXPORT_IF_KUNIT(amdgpu_dm_plane_fill_gfx12_plane_attributes_from_modifiers);
> +EXPORT_IF_KUNIT(amdgpu_dm_plane_fill_gfx12_attrs_from_modifiers);
> 
>   static void amdgpu_dm_plane_add_gfx10_1_modifiers(const struct 
> amdgpu_device *adev,
>                                                    uint64_t **mods,
> @@ -927,14 +927,14 @@ int 
> amdgpu_dm_plane_fill_plane_buffer_attributes(struct amdgpu_device *adev,
>          }
> 
>          if (adev->family == AMDGPU_FAMILY_GC_12_0_0) {
> -               ret = 
> amdgpu_dm_plane_fill_gfx12_plane_attributes_from_modifiers(adev, afb, 
> format,
> +               ret = 
> amdgpu_dm_plane_fill_gfx12_attrs_from_modifiers(adev, afb, format,
>                 rotation, plane_size,
>                 tiling_info, dcc,
>                 address);
>                  if (ret)
>                          return ret;
>          } else if (adev->family >= AMDGPU_FAMILY_AI) {
> -               ret = 
> amdgpu_dm_plane_fill_gfx9_plane_attributes_from_modifiers(adev, afb, 
> format,
> +               ret = 
> amdgpu_dm_plane_fill_gfx9_attrs_from_modifiers(adev, afb, format,
>                rotation, plane_size,
>                tiling_info, dcc,
>                address);
> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_plane.h b/ 
> drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_plane.h
> index 911fb2d73e22..55c33e051aee 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_plane.h
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_plane.h
> @@ -92,7 +92,7 @@ int amdgpu_dm_plane_get_plane_modifiers(struct 
> amdgpu_device *adev,
>   int amdgpu_dm_plane_get_plane_formats(const struct drm_plane *plane,
>                                        const struct dc_plane_cap 
> *plane_cap,
>                                        uint32_t *formats, int max_formats);
> -int amdgpu_dm_plane_fill_gfx9_plane_attributes_from_modifiers(struct 
> amdgpu_device *adev,
> +int amdgpu_dm_plane_fill_gfx9_attrs_from_modifiers(struct amdgpu_device 
> *adev,
> const struct amdgpu_framebuffer *afb,
> const enum surface_pixel_format format,
> const enum dc_rotation_angle rotation,
> @@ -100,7 +100,7 @@ int 
> amdgpu_dm_plane_fill_gfx9_plane_attributes_from_modifiers(struct 
> amdgpu_devi
> struct dc_tiling_info *tiling_info,
> struct dc_plane_dcc_param *dcc,
> struct dc_plane_address *address);
> -int amdgpu_dm_plane_fill_gfx12_plane_attributes_from_modifiers(struct 
> amdgpu_device *adev,
> +int amdgpu_dm_plane_fill_gfx12_attrs_from_modifiers(struct 
> amdgpu_device *adev,
>   const struct amdgpu_framebuffer *afb,
>   const enum surface_pixel_format format,
>   const enum dc_rotation_angle rotation,
> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/tests/ 
> amdgpu_dm_plane_test.c b/drivers/gpu/drm/amd/display/amdgpu_dm/tests/ 
> amdgpu_dm_plane_test.c
> index 46c9af432e37..fc84f5a08596 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/tests/amdgpu_dm_plane_test.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/tests/amdgpu_dm_plane_test.c
> @@ -579,7 +579,7 @@ static void 
> dm_test_fill_gfx12_plane_attributes_from_modifiers(struct kunit *tes
>          plane_size.surface_size.height = 1080;
> 
>          KUNIT_EXPECT_EQ(test,
> -  amdgpu_dm_plane_fill_gfx12_plane_attributes_from_modifiers(
> +  amdgpu_dm_plane_fill_gfx12_attrs_from_modifiers(
>                          adev, afb, SURFACE_PIXEL_FORMAT_GRPH_ARGB8888,
>                          ROTATION_ANGLE_0, &plane_size, &tiling_info, 
> &dcc, &address),
>                          0);
> @@ -623,7 +623,7 @@ static void 
> dm_test_fill_gfx9_plane_attributes_from_modifiers(struct kunit *test
>          afb->base.modifier = DRM_FORMAT_MOD_LINEAR;
> 
>          KUNIT_EXPECT_EQ(test,
> -  amdgpu_dm_plane_fill_gfx9_plane_attributes_from_modifiers(
> +  amdgpu_dm_plane_fill_gfx9_attrs_from_modifiers(
>                          adev, afb, SURFACE_PIXEL_FORMAT_GRPH_ARGB8888,
>                          ROTATION_ANGLE_0, &plane_size, &tiling_info, 
> &dcc, &address),
>                          0);
> @@ -1187,9 +1187,9 @@ static struct kunit_case 
> amdgpu_dm_plane_test_cases[] = {
>          KUNIT_CASE(dm_test_get_cursor_position),
>          /* amdgpu_dm_plane_format_mod_supported() */
>          KUNIT_CASE(dm_test_format_mod_supported),
> -       /* amdgpu_dm_plane_fill_gfx12_plane_attributes_from_modifiers() */
> +       /* amdgpu_dm_plane_fill_gfx12_attrs_from_modifiers() */
> KUNIT_CASE(dm_test_fill_gfx12_plane_attributes_from_modifiers),
> -       /* amdgpu_dm_plane_fill_gfx9_plane_attributes_from_modifiers() */
> +       /* amdgpu_dm_plane_fill_gfx9_attrs_from_modifiers() */
> KUNIT_CASE(dm_test_fill_gfx9_plane_attributes_from_modifiers),
>          /* amdgpu_dm_plane_helper_check_state() */
>          KUNIT_CASE(dm_test_helper_check_state_viewport_reject),
> (END)
> 
> 
> Regards,
> 
> Venkat.
> 
>>
>> # git bisect log
>> git bisect start
>> # status: waiting for both good and bad commits
>> # bad: [5c73cd9f0819c1c44e373e3dabb68318b1de1a12] Add linux-next 
>> specific files for 20260707
>> git bisect bad 5c73cd9f0819c1c44e373e3dabb68318b1de1a12
>> # good: [8cdeaa50eae8dad34885515f62559ee83e7e8dda] Linux 7.2-rc2
>> git bisect good 8cdeaa50eae8dad34885515f62559ee83e7e8dda
>> # good: [aac7863446a8e0cf380f4a5087bc3cdc9b8c14c0] Merge branch 
>> 'master' of https://git.kernel.org/pub/scm/linux/kernel/git/herbert/ 
>> cryptodev-2.6.git
>> git bisect good aac7863446a8e0cf380f4a5087bc3cdc9b8c14c0
>> # bad: [fe28d02cde5372d7f71cc6132ccdef37a98ac750] Merge branch 'for- 
>> linux-next' of https://gitlab.freedesktop.org/drm/i915/kernel.git
>> git bisect bad fe28d02cde5372d7f71cc6132ccdef37a98ac750
>> # good: [0639cb26862afe4e35a689a8b5df8b9117c19f52] Merge tag 'drm-xe- 
>> next-2026-07-03' of https://gitlab.freedesktop.org/drm/xe/kernel into 
>> drm-next
>> git bisect good 0639cb26862afe4e35a689a8b5df8b9117c19f52
>> # good: [4e9c8a9c322427055c4892183d266ba391af1bc8] drm/amdkfd: drop 
>> struct kfd_signal_page wrapper
>> git bisect good 4e9c8a9c322427055c4892183d266ba391af1bc8
>> # bad: [ea33aa1545535fdb4c1a208b7bfd63314c3a4aa2] drm/amdgpu: Drop 
>> legacy ACA log RAS error data code
>> git bisect bad ea33aa1545535fdb4c1a208b7bfd63314c3a4aa2
>> # good: [a17e79d01f22182a9fcbe79fcbe2ad1477d43e0f] drm/amd/pm: 
>> Validate pp_table header before reading size
>> git bisect good a17e79d01f22182a9fcbe79fcbe2ad1477d43e0f
>> # bad: [7a561c2b1b63abcffb55f625c0d0adb68ab2961a] drm/amd/display: 
>> Simplify boolean checks
>> git bisect bad 7a561c2b1b63abcffb55f625c0d0adb68ab2961a
>> # good: [53ef33c084c5778cc2dcd1efff25e31b6e231141] drm/amd/pm: 
>> Validate Tonga PPTable subtable bounds
>> git bisect good 53ef33c084c5778cc2dcd1efff25e31b6e231141
>> # good: [fe5966d4fdcbed91e6b3478ea6c89d9915d6ed4a] drm/amdkfd: move 
>> TBA/TMA from system to device memory
>> git bisect good fe5966d4fdcbed91e6b3478ea6c89d9915d6ed4a
>> # good: [7a39b1c3b2e6b27f4230a20ccf9ac5a2737fa8b0] drm/amd/display: 
>> Replace repeated no-native-i2c checks with force_i2c_over_aux field
>> git bisect good 7a39b1c3b2e6b27f4230a20ccf9ac5a2737fa8b0
>> # good: [88ae862060f05cd8279e764832f04eafafa505d8] drm/amd/display: 
>> Add more KUnit tests for amdgpu_dm_colorop
>> git bisect good 88ae862060f05cd8279e764832f04eafafa505d8
>> # bad: [2b147895be109e0860269a7a72c697cdf049a885] drm/amd/display: Add 
>> kunit tests for amdgpu_dm_plane
>> git bisect bad 2b147895be109e0860269a7a72c697cdf049a885
>> # first bad commit: [2b147895be109e0860269a7a72c697cdf049a885] drm/ 
>> amd/display: Add kunit tests for amdgpu_dm_plane
>>
>>>
>>>
>>> Regards,
>>>
>>> Venkat.
>>