amd64 kernel crash introduced between 20180329 & 20180408

[Dan Allen]

I run FreeBSD 11-STABLE on actual machines, and I build the system every few days.  Things have been fine.

However, I also run FreeBSD 11 via the qemu emulator on my Mac.  I run lots of different BSD & Linux OSes here to test them out.  I have been running the same binary of qemu-system-x86_64 v1.2 for six years.  It runs great.

Then recently this happened:

This snapshot dated 20180329, after doing a fresh install, runs fine:

  https://download.freebsd.org/ftp/snapshots/ISO-IMAGES/11.1/FreeBSD-11.1-STABLE-amd64-20180329-r331742-disc1.iso

I can run pkg install and begin adding stuff to the system and life is good.

BUT

This snapshot dated 20180408, after doing a fresh install, will crash when running pkg install:

  https://download.freebsd.org/ftp/snapshots/ISO-IMAGES/11.1/FreeBSD-11.1-STABLE-amd64-20180408-r332308-disc1.iso

It crashes about 90% of the way through updating the pkg snapshot.  It does not matter what pkg you try and install.

However, the latest release in the i386 flavor works fine on qemu:

  https://download.freebsd.org/ftp/snapshots/ISO-IMAGES/11.1/FreeBSD-11.1-STABLE-i386-20180412-r332428-disc1.iso

So sometime between March 29th & April 8th, in amd64 boot code, I believe the problem was introduced.

I cannot debug the crash, because it does a kernel dump, and then when the system reboots, almost anything again triggers a kernel crash and it reboots again and again: no chance to inspect a mini dump or whatever.

I wish I had more to go on, but I am happy to off list work with anyone that wants to pursue this, by testing out stuff or answering more questions.

Dan Allen
Running FreeBSD since 2.2.8