On 16.09.16 15:30, Christoffer Dall wrote: > On Fri, Sep 16, 2016 at 02:31:42PM +0200, Paolo Bonzini wrote: >> >> >> On 16/09/2016 14:30, Christoffer Dall wrote: >>>>>> This patch set allows user space to receive vtimer events as well as mask >>>>>> them, so that we can handle all vtimer related interrupt injection from user >>>>>> space, enabling us to use architected timer with user space gic emulation. >>>>> >>>>> I have already voiced my concerns in the past, including face to face, >>>>> and I'm going to repeat it: I not keen at all on adding a new userspace >>>>> interface that is going to bitrot extremely quickly. >>>> >>>> You don't have automated tests set up? It's not going to bitrot if you >>>> test it, either with kvm-unit-tests or just by smoke-testing Linux. >>>> It's _for_ the raspi, but it's not limited to it. >>> >>> Our automated testing situation is not great, no. Something we're >>> looking at, but have resource problems with. >> >> But it's not a good reason to hold back a feature... >> > > I didn't say that exactly, but choosing not to merge something we cannot > maintain and which we're not paid to look after and where there's a > minimal interest, is not entirely unreasonable. > > That being said, I'm not categorically against these patches, but I > share Marc's view that we've already seen that non-vgic support had been > broken for multiple versions without anyone complaining, and without > automated testing or substantial interest in the work, the patches > really are likely to bit-rot. I know that it's very hard to grasp from an upstream maintainer perspective, but keep in mind where the bulk of execution of kernel code lies. The average life cycle of a "stable" Linux distribution's kernel is a few years. So far all regressions in the user space gic code have been found within less than 1y of the respective code release. I'd say that counts for quite a well used feature. > But I haven't even looked at the patches in detail, I was just replying > to the comment about testing. Also keep in mind that without the architected timer support (and/or without qemu patches than enable user space timers) the user space gic support is pretty unusable to most people, so you obviously get less reports. Alex -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
