On Thu, 16 Nov 2017 09:25:27 -0500 Tony Krowiak <akrowiak@xxxxxxxxxxxxxxxxxx> wrote: > On 11/16/2017 07:35 AM, Cornelia Huck wrote: > > On Thu, 16 Nov 2017 13:02:26 +0100 > > Pierre Morel <pmorel@xxxxxxxxxxxxxxxxxx> 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@xxxxxxxxxxxxxxxxxx> 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). > > > > 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.] > Is it sufficient to specify 'depends on ZCRYPT && VFIO_MDEV_DEVICE' > since 'VFIO_MDEV_DEVICE depends on VFIO && VFIO_MDEV' and 'VFIO_MDEV > depends on VFIO' and 'VFIO depends on IOMMU_API'? Perhaps ZCRYPT && VFIO_MDEV && VFIO_MDEV_DEVICE, to make it a bit more obvious? [Also, is IOMMU_API only needed to satisfy dependencies?]
