On Tue, Apr 27, 2021 at 12:34 PM Paolo Bonzini <pbonzini@xxxxxxxxxx> wrote: > > On 27/04/21 08:01, Anup Patel wrote: > > Hi Paolo, > > > > Looks like it will take more time for KVM RISC-V to be merged under arch/riscv. > > > > Let's go ahead with your suggestion of having KVM RISC-V under drivers/staging > > so that development is not blocked. > > > > I will send-out v18 series which will add KVM RISC-V under the staging > > directory. > > > > Should we target Linux-5.14 ? > > Yes, 5.14 is reasonable. You'll have to adjust the MMU notifiers for > the new API introduced in 5.13. Sure, I will rebase on the new API introduced in 5.13 Regards, Anup > > Paolo > > > Regards, > > Anup > > > > On Tue, Apr 27, 2021 at 11:13 AM Paul Walmsley <paul.walmsley@xxxxxxxxxx> wrote: > >> > >> On Fri, 9 Apr 2021, Palmer Dabbelt wrote: > >> > >>> On Wed, 31 Mar 2021 02:21:58 PDT (-0700), pbonzini@xxxxxxxxxx wrote: > >>> > >>>> Palmer, are you okay with merging RISC-V KVM? Or should we place it in > >>>> drivers/staging/riscv/kvm? > >>> > >>> I'm certainly ready to drop my objections to merging the code based on > >>> it targeting a draft extension, but at a bare minimum I want to get a > >>> new policy in place that everyone can agree to for merging code. I've > >>> tried to draft up a new policy a handful of times this week, but I'm not > >>> really quite sure how to go about this: ultimately trying to build > >>> stable interfaces around an unstable ISA is just a losing battle. I've > >>> got a bunch of stuff going on right now, but I'll try to find some time > >>> to actually sit down and finish one. > >>> > >>> I know it might seem odd to complain about how slowly things are going > >>> and then throw up another roadblock, but I really do think this is a > >>> very important thing to get right. I'm just not sure how we're going to > >>> get anywhere with RISC-V without someone providing stability, so I want > >>> to make sure that whatever we do here can be done reliably. If we don't > >>> I'm worried the vendors are just going to go off and do their own > >>> software stacks, which will make getting everyone back on the same page > >>> very difficult. > >> > >> I sympathize with Paolo, Anup, and others also. Especially Anup, who has > >> been updating and carrying the hypervisor patches for a long time now. > >> And also Greentime, who has been carrying the V extension patches. The > >> RISC-V hypervisor specification, like several other RISC-V draft > >> specifications, is taking longer to transition to the officially "frozen" > >> stage than almost anyone in the RISC-V community would like. > >> > >> Since we share this frustration, the next questions are: > >> > >> - What are the root causes of the problem? > >> > >> - What's the right forum to address the root causes? > >> > >> To me, the root causes of the problems described in this thread aren't > >> with the arch/riscv kernel maintenance guidelines, but rather with the > >> RISC-V specification process itself. And the right forum to address > >> issues with the RISC-V specification process is with RISC-V International > >> itself: the mailing lists, the participants, and the board of directors. > >> Part of the challenge -- not simply with RISC-V, but with the Linux kernel > >> or any other community -- is to ensure that incentives (and disincentives) > >> are aligned with the appropriately responsible parts of the community. > >> And when it comes to specification development, the right focus to align > >> those incentives and disincentives is on RISC-V International. > >> > >> The arch/riscv patch acceptance guidelines are simply intended to ensure > >> that the definition of what is and isn't RISC-V remains clear and > >> unambiguous. Even though the guidelines can result in short-term pain, > >> the intention is to promote long-term stability and sustainable > >> maintainability - particularly since the specifications get baked into > >> hardware. We've observed that attempting to chase draft specifications > >> can cause significant churn: for example, the history of the RISC-V vector > >> specification illustrates how a draft extension can undergo major, > >> unexpected revisions throughout its journey towards ratification. One of > >> our responsibilities as kernel developers is to minimize that churn - not > >> simply for our own sanity, or for the usability of RISC-V, but to ensure > >> that we remain members in good standing of the broader kernel community. > >> Those of us who were around for the ARM32 and ARM SoC kernel accelerando > >> absorbed strong lessons in maintainability, and I doubt anyone here is > >> interested in re-learning those the hard way. > >> > >> RVI states that the association is open to community participation. The > >> organizations that have joined RVI, I believe, have a strong stake in the > >> health of the RISC-V ecosystem, just as the folks have here in this > >> discussion. If the goal really is to get quality specifications out the > >> door faster, then let's focus the energy towards building consensus > >> towards improving the process at RISC-V International. If that's > >> possible, the benefits won't only accrue to Linux developers, but to the > >> entire RISC-V hardware and software development community at large. If > >> nothing else, it will be an interesting test of whether RISC-V > >> International can take action to address these concerns and balance them > >> with those of other stakeholders in the process. > >> > >> > >> - Paul > > >
