On 2011-02-01 18:20, Anthony Liguori wrote: > On 02/01/2011 11:03 AM, Jan Kiszka wrote: >> On 2011-02-01 17:53, Anthony Liguori wrote: >> >>> On 02/01/2011 10:36 AM, Jan Kiszka wrote: >>> >>>> On 2011-02-01 16:54, Chris Wright wrote: >>>> >>>> >>>>> KVM upstream merge: status, plans, coordination >>>>> - Jan has a git tree, consolidating >>>>> - qemu-kvm io threading is still an issue >>>>> - Anthony wants to just merge >>>>> - concerns with non-x86 arch and merge >>>>> - concerns with big-bang patch merge and following stability >>>>> - post 0.14 conversion to glib mainloop, non-upstreamed qemu-kvm will be >>>>> a problem if it's not there by then >>>>> - testing and nuances are still an issue (e.g. stefan berger's mmio read issue) >>>>> - qemu-kvm still evolving, needs to get sync'd or it will keep diverging >>>>> - 2 implementations of main init, cpu init, Jan has merged them into one >>>>> - qemu-kvm-x86.c file that's only a few hundred lines >>>>> - review as one patch to see the fundamental difference >>>>> >>>>> >>>> More precisely, my current work flow is to pick some function(s), e.g. >>>> kvm_cpu_exec/kvm_run, and start wondering "What needs to be done to >>>> upstream so that qemu-kvm could use that implementation?". If they >>>> differ, the reasons need to be understood and patched away, either by >>>> fixing/enhancing upstream or simplifying qemu-kvm. Once the upstream >>>> changes are merged back, a qemu-kvm patch is posted to switch to that >>>> version. >>>> >>>> Any help will be welcome, either via review of my subtle regressions or >>>> on resolving concrete differences. >>>> >>>> E.g. posix-aio-compat.c: Why does qemu-kvm differ here? If it's because >>>> of its own iothread code, can we wrap that away or do we need to >>>> consolidate the threading code first? Or do we need to fix something in >>>> upstream? >>>> >>>> >>> I bet it's the eventfd thing. It's arbitrary. If you've got a small >>> diff post your series, I'd be happy to take a look at it and see what I >>> can explain. >>> >>> >> Looks like it's around signalfd and its emulation: >> > > I really meant the compatfd thing. > > signalfd can't really be emulated properly so in upstream we switched to > a pipe() which Avi didn't like. > > But with glib, this all goes away anyway so we should just drop the > qemu-kvm changes and use the upstream version. Once we enable I/O > thread in qemu.git, we no longer need to use signals for I/O completion > which I think everyone would agree is a better solution. Don't understand: If we do not need SIGIO for AIO emulation in threaded mode, why wasn't that stubbed out already? If that helps reducing worries about the signalfd emulation (which is likely a non-issue anyway as anyone with serious workload should run a kernel with such support). Jan -- Siemens AG, Corporate Technology, CT T DE IT 1 Corporate Competence Center Embedded Linux -- 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
