QEMU 2.6.0 in SDK does not implement IA hardware tasks and MMU properly

[zephyrbot]

Reported by Andrew Boie:

To implement x86 stack protection, I need the CPU to do an IA hardware task switch to a special exception IA task that has a known good stack when a double fault exception occurs.

QEMU 2.6.0 (the version in our SDK) does not implement this properly and either aborts to the command line or issues a spurious page fault exception instead. If I disable the MMU the task switching works fine.

I have found that QEMU 2.9.0 that comes with Fedora, does not have this problem.

I'm requesting we either update the QEMU for x86 in the SDK, or backport whatever patches fixed the issue with task switching and the MMU.

Enabling stack protection on x86 is blocked until this is fixed.

(Imported from Jira ZEP-2394)

[zephyrbot]

by Andrew Boie:

PEBCAK

[zephyrbot]

Blocks GH-3626