On Wed, 2020-01-22 at 14:57 +0000, Andrew Cooper wrote: > On 22/01/2020 01:58, Bobby Eshleman wrote: > > Hey everybody, > > > > This is an RFC patchset for the very beginnings of adding RISC-V > > support > > to Xen. This RFC is really just to start a dialogue about > > supporting > > RISC-V and align with the Xen project and community before going > > further. For that reason, it is very rough and very incomplete. > > > > My name is Bobby Eshleman, I'm a software engineer at > > Star Lab / Wind River on the ARM team, mostly having worked in the > > Linux > > kernel. I've also been involved a good amount with Xen on ARM > > here, > > mostly dealing with tooling, deployment, and testing. A lot of > > this > > patchset is heavily inspired by the Xen/ARM source code > > (particularly > > the early setup up code). > > > > Currently, this patchset really only sets up virtual memory for Xen > > and > > initializes UART to enable print output. None of RISC-V's > > virtualization support has been implemented yet, although that is > > the > > next road to start going down. Many functions only contain dummy > > implementations. Many shortcuts have been taken and TODO's have > > been > > left accordingly. It is very, very rough. Be forewarned: you are > > quite > > likely to see some ungainly code here (despite my efforts to clean > > it up > > before sending this patchset out). My intent with this RFC is to > > align > > early and gauge interest, as opposed to presenting a totally > > complete > > patchset. > > > > Because the ARM and RISC-V use cases will likely bear resemblance, > > the > > RISC-V port should probably respect the design considerations that > > have > > been laid out and respected by Xen on ARM for dom0less, safety > > certification, etc... My inclination has been to initially target > > or > > prioritize dom0less (without excluding dom0full) and use the ARM > > dom0less implementation as a model to follow. I'd love feedback on > > this > > point and on how the Xen project might envision a RISC-V > > implementation. > > > > This patchset has _some_ code for future support for 32-bit, but > > currently my focus is on 64-bit. > > > > Again, this is a very, very rough and totally incomplete > > patchset. My > > goal here is just to gauge community interest, begin discussing > > what Xen > > on RISC-V may look like, receive feedback, and see if I'm heading > > in the > > right direction. > > > > My big questions are: > > Does the Xen project have interest in RISC-V? > > There is very large downstream interest in RISC-V. So a definite > yes. > > > What can be done to make the RISC-V port as upstreamable as > > possible? > > Any major pitfalls? > > > > It would be great to hear all of your feedback. > > Both RISC-V and Power9 are frequently requested things, and both > suffer > from the fact that, while we as a community would like them, the > upstream intersection of "people who know Xen" and "people who know > enough arch $X to do an initial port" is 0. > > This series clearly demonstrates a change in the status quo, and I > think > a lot of people will be happy. > > To get RISC-V to being fully supported, we will ultimately need to > get > hardware into the CI system, and an easy way for developers to test > changes. Do you have any thoughts on production RISC-V hardware > (ideally server form factor) for the CI system, and/or dev boards > which > might be available fairly cheaply?
AFAIK this is awhile off. The Hypervisor spec is still in a draft state (expecting to be frozen this year) so right now QEMU is the only option. Alistair > > How much time do you have to put towards the port? Is this something > in > your free time, or something you are doing as part of work? > Ultimately, > we are going to need to increase the level of RISC-V knowledge in the > community to maintain things in the future. > > Other than that, very RFC series are entirely fine. A good first > step > would be simply to get the build working, and get some kind of > cross-compile build in CI, to make sure that we don't clobber the > RISC-V > build with common or other-arch changes. > > I hope this helps. > > ~Andrew _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
