Re: [PATCH v4 1/2] drivers/s390/char: Add Ultravisor io device

Steffen Eiden
2022-05-18T13:50:15Z

On 5/18/22 15:45, Janosch Frank wrote:
> On 5/18/22 13:47, Heiko Carstens wrote:
>> On Tue, May 10, 2022 at 02:47:23PM +0000, Steffen Eiden wrote:
>>> diff --git a/drivers/s390/char/Kconfig b/drivers/s390/char/Kconfig
>>> index 6cc4b19acf85..e9b9902abbaf 100644
>>> --- a/drivers/s390/char/Kconfig
>>> +++ b/drivers/s390/char/Kconfig
>>> @@ -100,6 +100,16 @@ config SCLP_OFB
>>>         This option enables the Open-for-Business interface to the s390
>>>         Service Element.
>>> +config S390_UV_UAPI
>>> +    def_tristate y
>>> +    prompt "Ultravisor userspace API"
>>> +    help
>>> +      Selecting exposes parts of the UV interface to userspace
>>> +      by providing a misc character device at /dev/uv.
>>> +      Using IOCTLs one can interact with the UV.
>>> +      The device is only available if the Ultravisor
>>> +      Facility (158) is present.
>>
>> Is there a reason why this is default "y"? If you think this should be
>> compiled into the kernel if used, then why allow to make it a module
>> at all?
>> Instead you could get rid of a couple if lines of code.
>
> There was a lot of discussion around this already and the "Y" was chosen
> as auto-loading this is a pain and therefore the SCLP and CHSC-Misc set
> it to Y and we took that as an example (Steffen spoke to Peter to get
> guidance).
>
> I'm sure that we want the possibility to have this as a module.
> Personally I'd choose "m" over "y" since the module is only useful for a
> very small amount of users.

I am fine with changing "y" to "m".

Steffen