Hi, it's the first time I did a kernel bisection. If I did it correctly, commit 92a0f81d89571e3e8759366e050ee05cc545ef99 (x86/cpu_entry_area: Move it out of the fixmap, on Wed Dec 20), is causing the following issue on certain hardware: > Loading Linux 4.15 ... > Loading initial ramdisk ... > <immediate reboot> * I can reproduce this issue on an i5-4440 with any 32bit kernel after that commit, and up to yesterday's linux-stable. * I cannot reproduce it on 64bit kernels. * I cannot reproduce it on an i3-4150 on the same motherboard Gigabyte B85M-HD3, so maybe it's related to the number of cores? * Also if I put acpi=off in the kernel command line, it works around the issue. About 10 schools have already reported the issue, so I believe it's rather common... I'm able to test kernels or patches. Thank you!
The problem still happens with 4.15rc9, i.e. 32 bit kernels immediately reboot on at least i5-4440 and i5-4460.
I tested a few more CPUs, 32 bit kernels no longer work on: i5-3470, i5-4440, i5-4460, i5-6200U ...and yet they work properly on: i3-4170, i3-7100, i5-4590, Q6600, Q8300 The "acpi=off" parameter sometimes helped, sometimes not.
The issue has also been reported in launchpad: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1745118 Wgrant posted a fix there which works for me. He also sent it upstream in the kernel: https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/patch/?id=55f49fcb879fbeebf2a8c1ac7c9e6d90df55f798 Thanks a lot William!