kern/189355: [zfs] zfs panic on root mount 10-stable

[Radim Kolar]

its not just about building custom kernel. GENERIC from 10-STABLE panics on i386 mount ZFS root too.

Maybe ZFS should not be used on i386, but it should not panic system. If you are against changing default kernel configuration on i386 then add another warning to boot messages similar to this:

ZFS WARNING: Recommended minimum kmem_size is 512MB; expect unstable behavior.
             Consider tuning vm.kmem_size and vm.kmem_size_max
             in /boot/loader.conf.