Subject: Re: [PATCH v4 1/4] kernel: param: initialize module_kset before do_initcalls()

From: Jon Hunter <[email-masked]>
Date: Tue, 12 May 2026 09:55:03 +0100

Hi Shashank,

On 12/05/2026 03:12, Shashank Balaji wrote:

...

>> Hi Thierry and Jonathan,
>>
>> You can find the context for this email in this patch:
>> https://lore.kernel.org/all/[email-masked]/
>>
>> TL;DR: tegra194_cbb_driver and tegra234_cbb_driver are the only drivers
>> registering themselves as early as in a pure_initcall. This is a problem
>> on two fronts:
>> 1. Philosophical: As Gary pointed out, pure_initcalls are intended to purely
>> initialize variables that couldn't be statically initialized. But these
>> are doing driver registrations.
>> 2. module_kset not initialized at pure_initcall stage: This is needed to
>> set the module sysfs symlink. Since module_kset is not alive yet during
>> pure_initcalls, registering these drivers panics the kernel.

Where exactly is this panic seen? Ie. why are we not seeing this?

>> We would like to do the tegra cbb driver registration in a core_initcall
>> (or some later initcall works too), and move module_kset initialization
>> to a pure_initcall. Like this:
>>
>> diff --git a/drivers/soc/tegra/cbb/tegra194-cbb.c b/drivers/soc/tegra/cbb/tegra194-cbb.c
>> index ab75d50cc85c..2f69e104c838 100644
>> --- a/drivers/soc/tegra/cbb/tegra194-cbb.c
>> +++ b/drivers/soc/tegra/cbb/tegra194-cbb.c
>> @@ -2342,7 +2342,7 @@ static int __init tegra194_cbb_init(void)
>>   {
>>          return platform_driver_register(&tegra194_cbb_driver);
>>   }
>> -pure_initcall(tegra194_cbb_init);
>> +core_initcall(tegra194_cbb_init);
>>
>>   static void __exit tegra194_cbb_exit(void)
>>   {
>> diff --git a/drivers/soc/tegra/cbb/tegra234-cbb.c b/drivers/soc/tegra/cbb/tegra234-cbb.c
>> index fb26f085f691..785072fa4e85 100644
>> --- a/drivers/soc/tegra/cbb/tegra234-cbb.c
>> +++ b/drivers/soc/tegra/cbb/tegra234-cbb.c
>> @@ -1774,7 +1774,7 @@ static int __init tegra234_cbb_init(void)
>>   {
>>          return platform_driver_register(&tegra234_cbb_driver);
>>   }
>> -pure_initcall(tegra234_cbb_init);
>> +core_initcall(tegra234_cbb_init);
>>
>>   static void __exit tegra234_cbb_exit(void)
>>   {
>>
>> Would this work?

I am adding Sumit who has been doing a lot of the Tegra CBB driver work.

Sumit, any concerns here? We could run this change through our internal 
testing to confirm.

Jon

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nvpublic