OK, other than the dkms issues, 4.2.0 rc8 did install enough to boot (just didn't have wifi), and it does boot in SMP mode:
bladernr@Bun-Bun:~$ uname -a Linux Bun-Bun 4.2.0-040200rc8-generic #201508240030 SMP Mon Aug 24 04:31:40 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux bladernr@Bun-Bun:~$ cat /proc/cpuinfo |grep ocessor processor : 0 processor : 1 processor : 2 processor : 3 so with 4.2.0 rc8, at least, I can boot in SMP mode, and all four CPUs appear (two cores at 2 threads each). -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux-lts-utopic in Ubuntu. https://bugs.launchpad.net/bugs/1487621 Title: Fails to boot on Macbook Air 2013 (Haswell) Status in linux-lts-utopic package in Ubuntu: New Status in linux-lts-vivid package in Ubuntu: New Bug description: I keep running into issues with booting on a 2013 Macbook Air. After grub, the kernel and initrd load and the system then just hangs with a blinking cursor. Removing the "quiet" and "splash" options shows me that the kernel hangs bringing up SMP, just as in bug #1197451 which has been marked Fix Released already (some time ago, actually). I get exactly what was mentioned in the comments about SMP hanging and have had to manually inject nosmp into the boot command when I boot the machine. ProblemType: Bug DistroRelease: Ubuntu 14.04 Package: linux-image-3.16.0-40-generic 3.16.0-40.54~14.04.1 ProcVersionSignature: Ubuntu 3.16.0-40.54~14.04.1-generic 3.16.7-ckt11 Uname: Linux 3.16.0-40-generic x86_64 NonfreeKernelModules: wl ApportVersion: 2.14.1-0ubuntu3.12 Architecture: amd64 CurrentDesktop: Unity Date: Fri Aug 21 17:17:40 2015 InstallationDate: Installed on 2015-06-11 (71 days ago) InstallationMedia: Ubuntu 14.04.2 LTS "Trusty Tahr" - Release amd64+mac (20150218.1) SourcePackage: linux-lts-utopic UpgradeStatus: No upgrade log present (probably fresh install) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux-lts-utopic/+bug/1487621/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
