On 01/30/15 11:48, Daniel P. Berrange wrote: > On Fri, Jan 30, 2015 at 10:29:46AM +0000, Peter Maydell wrote: >> On 30 January 2015 at 09:54, Daniel P. Berrange <berra...@redhat.com> wrote: >>> While it is clear there is no solution that works correctly with all >>> kernels, I hate to think that we're going to stick with an ordering >>> that is clearly wrong for modern kernels, forever going forward. The >>> aarch64 world is only just starting out, so on balance I think we >>> should optimize for the future rather than the past, since that gives >>> right behaviour for orders of magnitude more people in the long term. >> >> Yeah, I agree it's awkward. But I hate breaking people's >> working setups, and we have no guarantee the kernel won't >> change again in the future. >> >> You could try asking the kernel folk to revert that patch on >> the basis that it breaks things... > > Might be worth a shot - the patch is only a month old. Or at least do a > followup patch to put the ordering back the way it was, rather than plain > revert
Please note that (as far as I understand) the patch that I referenced is indeed very new, it's not part of v3.18, but the reversal can easily be seen with v3.18. In other words, the kernel patch I referenced introduces no functional change, it just reorganizes stuff in the kernel (AIUI), with the benefit of killing a superfluous field. The reason I referenced it because its *commit message* gives good background. If we really wanted to find the kernel change that reversed the traversal, we'd have to talk to Grant and/or bisect the kernel. Thanks Laszlo > Long term though it will be much better of AArch64 would just do PCI > instead of MMIO bus. Then we have proper device addressing which we > can control in a predictable manner that will be stable across hotplug > and unplug and migration. I hear there's work on PCI for AArch64 but > is there a near term ETA yet ? > > Regards, > Daniel >
