On Wed, 26 May 2021 09:18:27 +0100, Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> wrote: > > Hi Marc, > > On Wed, May 26, 2021 at 10:01 AM Marc Zyngier <maz@xxxxxxxxxx> wrote: > > On Wed, 26 May 2021 08:52:42 +0100, > > Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> wrote: > > > On Tue, May 11, 2021 at 11:13 AM Marc Zyngier <maz@xxxxxxxxxx> wrote: > > > > On 2021-05-11 10:07, Geert Uytterhoeven wrote: > > > > > On Tue, Mar 30, 2021 at 4:56 PM Marc Zyngier <maz@xxxxxxxxxx> wrote: > > > > >> From: Jianyong Wu <jianyong.wu@xxxxxxx> > > > > > > > > > >> --- a/drivers/ptp/Kconfig > > > > >> +++ b/drivers/ptp/Kconfig > > > > >> @@ -108,7 +108,7 @@ config PTP_1588_CLOCK_PCH > > > > >> config PTP_1588_CLOCK_KVM > > > > >> tristate "KVM virtual PTP clock" > > > > >> depends on PTP_1588_CLOCK > > > > >> - depends on KVM_GUEST && X86 > > > > >> + depends on (KVM_GUEST && X86) || (HAVE_ARM_SMCCC_DISCOVERY && > > > > >> ARM_ARCH_TIMER) > > > > > > > > > > Why does this not depend on KVM_GUEST on ARM? > > > > > I.e. shouldn't the dependency be: > > > > > > > > > > KVM_GUEST && (X86 || (HAVE_ARM_SMCCC_DISCOVERY && ARM_ARCH_TIMER)) > > > > > > > > > > ? > > > > > > > > arm/arm64 do not select KVM_GUEST. Any kernel can be used for a guest, > > > > and KVM/arm64 doesn't know about this configuration symbol. > > > > > > OK. > > > > > > Does PTP_1588_CLOCK_KVM need to default to yes? > > > Perhaps only on X86, to maintain the status quo? > > > > I think I don't really understand the problem you are trying to > > solve. Is it that 'make oldconfig' now asks you about this new driver? > > Why is that an issue? > > My first "problem" was that it asked about this new driver on > arm/arm64, while I assumed there were some missing dependencies > (configuring a kernel should not ask useless questions). That turned > out to be a wrong assumption, so there is no such problem here. > > The second problem is "default y": code that is not critical should > not be enabled by default. Hence my last question. I think consistency between architectures is important. Certainly, distributions depend on that, and we otherwise end-up with distro kernels missing functionalities. The notion of "critical" is also pretty relative. defconfig contains a gazillion of things that are not critical to most people, for example, and yet misses a bunch of things that are needed to boot on some of my systems. That's just to say that I find it difficult to make that choice from the PoV of a kernel hacker. I'm personally more inclined to leave things enabled and let people *disable* things if they want to reduce the footprint of their kernel. Thanks, M. -- Without deviation from the norm, progress is not possible.
