On Mon, Dec 15, 2014 at 7:08 PM, Adam Conrad <[email protected]> wrote: > On Mon, Dec 15, 2014 at 05:36:25PM -0700, Dann Frazier wrote: >> >> There's the question of whether or not we would be penalizing the >> performance of other classes of workloads people want to run on arm64. >> If there are some representative tests we should be looking at, please >> let me know. > > So, this is the obvious concern, and it only makes logical sense that > many workloads will perform better with a smaller page size, as if you > don't actually need the giant loads, you'll be flushing fewer caches > for nothing. But, I'll put my money where my mouth is and see if I can > find benchmarks to back up that hand-waving. > >> I'm not sure how much interest there is for ARMv7 compat in Ubuntu. >> There is the developer use case of using the same hardware for armhf >> and arm64 porting - which, theoretically, we could also achieve by >> rebuilding those ports w/ an updated binutils. But otherwise, I'm not >> aware of many legacy ARMv7 apps that users are likely to want to bring >> over to Ubuntu/arm64 that couldn't be rebuilt. > > So, retroactively rebuilding all our already released dists is clearly > not an option, and I hadn't even thought about this armv7 compat issue. > > This does impact our previous master plan for scrapping our armv7 build > infrastructure and building armhf on arm64 in chroots, like we do for > all our other 64/32 port pairs. > > Now, if qemu-system-arm --enable-kvm happens to work on arm64 (with 64k > pages), this might be a non-issue, as we can run fully accelerated v7 > VMs on our v8 kit, and that would serve just as well as 32-on-64 with > chroots. Is that possible? Does it work today? If not, is there any > one working on making it work?
There appears to be work to address 32-on-64 KVM upstream, but it does not work today. While testing this I discovered a (very likely platform-specific) issue on my test system that causes kvm to fail to init on 64K hosts. I'll investigate that in the background. -- ubuntu-devel mailing list [email protected] Modify settings or unsubscribe at: https://lists.ubuntu.com/mailman/listinfo/ubuntu-devel
