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.]
