[ubuntu] (Ubuntu 16.04) Boot issues with ACPI and touchscreen on Lenovo Yoga 710

I've been trying to get an install of Ubuntu 16.04 ruing on a new Lenovo Yoga 710, from a USB drive. At first the laptop would only boot inconsistently, and would often hang (usually irrecoverably) at random intervals during the boot.
So I changed the boot line (grub bootloader) to remove

to see debug info and try to find the error. Apparently, there's some kind of routing conflict during boot that causes a bunch of modules to be linked in when they shouldn't be (they don't seem to be consistent over multiple boots, but some such as hid_multitouch hid_force_sensor and a whole group of "snd" modules are always present when the error comes up). In any case, its an error in "kmem cache alloc" that causes some kind of recursive fault and hangs the CPU.

Following advice from other posts on this forum and installation guides for Ubuntu on other Lenovo models, I experimented booting with various ACPI options as on this page: https://01.org/linux-acpi/documentat...ux-acpi-issues. I quickly discovered that

allowed the laptop to boot consistently, but still had errors. Based on this page: https://wiki.ubuntu.com/DebuggingACPI I would have concluded that "the issue is in the ACPI table parsing code itself, or perhaps the SMP code" (and this may still be true, I'm still very new to Linux!), but I've also found that allows consistent booting.Since tuing off ACPI IRQ routing is a lot less important to me than tuing off ACPI power/fan management for a successful boot, I would normally be content to edit the grub command line to include acpi=noirq and leave it there. However using this option also seems to disable the Yoga's touchscreen, which is something I'd very much like to keep. I've read a lot of threads suggesting that this is just a keel/hardware compatibility issue, i.e. there's nothing I can do about it. But if that's the case then why does a clean boot occasionally work just fine? (touchscreen included!) And why do all the other input devices on the laptop work with acpi=off or acpi=noirq? Maybe these are foolish questions, but while I'm at it, is there no way to enable the touchscreen post-boot?

In fact, on the rare occasions when the system does boot normally the only mention of a touchscreen I can find using

is a single line referencing the fact that the module hid_multitouch has received input from SYNA750 and assigned it to port so and so, which is apparently the name of my Synaptics touchscreen (it shows up as this in "xinput," though not in "lsusb" when its working). When its working, I can also probe the port its coected to (usually /dev/event9) from a VM using evtest and get a satisfying response whenever I touch the screen, but when booting with acpi=noirq its as if it doesn't exist. It doesn't show up in xinput, lsusb, or lspci so far as I can tell, and probing every serial port at /dev/tty# doesn't get any response. Is it just not tuing on?

Someone with a different system and different touchscreen suggests on this thread: https://bbs.archlinux.org/viewtopic.php?id=133851 that hid_multitouch itself might be causing boot problems, but trying the solution posted there (blacklist hid_multitouch and reload it later on during boot) didn't work. However, based on posts like this one: http://ubuntuforums.org/archive/inde...t-2082116.html I have hope that I can just write some kind of script to enable the touchscreen with modprobe and ? I've tried and failed to do so using the touchscreen ID numbers retrieved from dmesg during a successful boot, but I'm pretty sure I'm using the wrong ones...

Other things I've tried: Booting with pci=biosirq, nomodeset, acpi_osi=Linux acpi_osi=Windows etc. etc.
Any advice would be greatly appreciated! Please pardon any newbie mistakes/not enough info, I'll try to provide whatever else I can.