2016-02-27 7:06 GMT-05:00 Christoffer Dall <christoffer.dall@xxxxxxxxxx>: > On Fri, Feb 26, 2016 at 10:53:44AM -0500, xu mike wrote: >> 2016-02-26 2:54 GMT-05:00 Christoffer Dall <christoffer.dall@xxxxxxxxxx>: >> > On Thu, Feb 25, 2016 at 12:45:45PM -0500, xu mike wrote: >> >> Hi Peter, >> >> >> >> 2016-02-25 10:30 GMT-05:00 Peter Maydell <peter.maydell@xxxxxxxxxx>: >> >> > >> >> > On 25 February 2016 at 15:17, xu mike <upennmike@xxxxxxxxx> wrote: >> >> > > I'm a student from the University of Pennsylvania. I want to try KVM on ARM >> >> > > boards. >> >> > > >> >> > > I have a Freescale IMX6 board [1] which has ARM Cortex A9 processors. >> >> > > I'm wondering if KVM can run on the Freescale IMX6 board? or >> >> > > Can KVM run on any ARM board with ARM Cortex A9 processors? >> >> > > >> >> > > I noticed at [2] that " KVM/ARM is designed specifically to work on ARM >> >> > > processors with the virtualization extensions enabled to run unmodified >> >> > > guest operating systems." >> >> > > I'm wondering if this statement is still true? >> >> > >> >> > Yes, it is. You need a CPU with the virtualization extensions, >> >> > and the A9 does not have them. You want (for instance) an A15 >> >> > or an A7. There are cheap A7-based development boards out there, >> >> > for instance the CubieTruck (which is not very fast but can run >> >> > a mainline Linux kernel and KVM so is a reasonable getting-started >> >> > development platform). >> >> >> >> >> >> Thank you very much for your quick reply! >> >> >> >> I'm wondering if KVM community has any plan to make KVM compatible >> >> with Cortex A9 processors? >> >> >> > >> > Not that I'm aware, no. >> > >> >> If someone, with linux scheduler development experiment but without >> >> porting experiment, wants to port KVM to Cortex A9, how hard could it >> >> be to port KVM onto Cortex A9 processor? >> > >> > As Peter said, ARM is not a virtualizable architecture, so you need >> > hardware support for virtualization to run hypervisors on an ARM system. >> > >> > Cortex-A9 does not have this support. >> > >> > You could implement something using either binary translation or >> > paravirtualization, but neither is something we're immediately >> > interested in accepting in mainline Linux. >> >> Right. I couldn't estimate how hard it will be to achieve the >> paravirtualization/binary translation in KVM.. Probably it may involve >> a lot of (assembly) code, since it requires to de-privilege those >> privileged instructions. :-( >> > > I don't think you'd have to write a lot of assembly code, but writing an > in-kernel binary translator is simply beyond the scope of what KVM was > designed for, and making a binary translator efficient and adding > support for shadow page tables will be non-trivial. I see... :-( > > If anything, but again, I stress that I would *not* accept this upstream, > you could build something that was paravirtualized with shadow page > table support. Ahha, it's totally understandable... > >> > >> > What is your use-case for running on A9 specifically, as opposed to a >> > CPU with virt support? >> >> The reason why I have to use A9 is because A9 has the special cache >> controller, called PL310 cache controller, which is not supported in >> A7 or A15. I want to use the special cache controller in >> virtualization environment. That's why I'm so addicted to A9. :-( >> If there is some latest ARM processor that has the PL310 cache >> controller and virtulaizaiton extension support, that will be awesome! >> However, I'm unaware of the ideal ARM processors. :-( Do you happen to >> know? >> > > I have no idea, no. I'm curious, why is it important for you to have a > PL310 cache controller in a VM? > > Is this research or product oriented? It's more for research. We want to see if we can control the L2 cache resource to provide better performance for the VMs. > > In any case, I would give up on A9 virtualization and use a proper piece > of hardware for virtualization on ARM. I see.. Now I guess I may have to give up A9 for virtualizaiotn. :-( Thank you very much for your time and help! Best, Mike _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
