Messages in this thread | | | Subject | Re: [RFC 05/19] s390/zcrypt: base implementation of AP matrix device driver | From | Pierre Morel <> | Date | Thu, 16 Nov 2017 15:25:28 +0100 |
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On 16/11/2017 13:35, Cornelia Huck wrote: > On Thu, 16 Nov 2017 13:02:26 +0100 > Pierre Morel <pmorel@linux.vnet.ibm.com> wrote: > >> On 14/11/2017 17:37, Tony Krowiak wrote: >>> On 11/14/2017 07:40 AM, Cornelia Huck wrote: >>>> On Fri, 13 Oct 2017 13:38:50 -0400 >>>> Tony Krowiak <akrowiak@linux.vnet.ibm.com> wrote: > >>>>> diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig >>>>> index 48af970..411c19a 100644 >>>>> --- a/arch/s390/Kconfig >>>>> +++ b/arch/s390/Kconfig >>>>> @@ -722,6 +722,19 @@ config VFIO_CCW >>>>> To compile this driver as a module, choose M here: the >>>>> module will be called vfio_ccw. >>>>> +config VFIO_AP_MATRIX >>>>> + def_tristate m >>>>> + prompt "Support for Adjunct Processor Matrix device interface" >>>>> + depends on ZCRYPT >>>>> + select VFIO >>>>> + select MDEV >>>>> + select VFIO_MDEV >>>>> + select VFIO_MDEV_DEVICE >>>>> + select IOMMU_API >>>> I think the more common pattern is to depend on the VFIO configs >>>> instead of selecting them. >>> It's ironic because I originally changed from using 'depends on' and >>> changed it based on review comments made >>> on our internal mailing list. I'll go with 'depends on'. >> >> Is doing like the others a sufficient good reason? >> What if the first who did this did not really think about it? >> >> When an administrator configure the kernel what does he think? >> >> - I want to have AP through AP_VFIO in my guests >> and he get implicitly VFIO >> or >> - I want to have VFIO >> and he has to explicitly add AP_VFIO too >> >> It seems to me that the first is much more user friendly. >> >> Please tell me if I missed something. dependencies? collateral damages? >> my logic is wrong? > > Using select for anything that's not a simple infrastructure dependency > may lead into trouble (we've had issues in the past where options tried > to enable other options but missed dependencies).
Understood, using dependencies is safer against a third party introducing a bug that would add a dependency to a member of the list but not update our list of selections.
> > If a user wants to use vfio-ap, I think it is reasonable to expect them > to figure out that they need both ap and vfio for that. > > [And config help has gotten much better than it was years ago; it's not > that hard to figure out what is actually needed.] >
OK for Darwin selection for admins, (a gentle Darwin :) I acknowledge) and on our side we spare to us running after our disappeared AP VFIO.
Regards,
Pierre
-- Pierre Morel Linux/KVM/QEMU in Böblingen - Germany
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