ZFS on root booting broken somewhere after r270020

[Kimmo Paasiala]

On 19.8.2014, at 10.46, Konstantin Belousov <kostikbel at gmail.com> wrote:

> On Tue, Aug 19, 2014 at 10:32:08AM +0300, Kimmo Paasiala wrote:
>> 
>> On 19.8.2014, at 10.10, Konstantin Belousov <kostikbel at gmail.com> wrote:
>> 
>>> On Tue, Aug 19, 2014 at 07:40:46AM +0300, Kimmo Paasiala wrote:
>>>> 
>>>> On 18.8.2014, at 8.54, Kimmo Paasiala <kpaasial at icloud.com> wrote:
>>>> 
>>>>> 
>>>>> On 18.8.2014, at 2.32, Kimmo Paasiala <kpaasial at icloud.com> wrote:
>>>>> 
>>>>>> System is:
>>>>>> 
>>>>>> FreeBSD freebsd10.rdnzl.info 10.0-STABLE FreeBSD 10.0-STABLE #2 r270020: Fri Aug 15 20:38:59 EEST 2014     kimmo at buildstable10amd64.rdnzl.info:/usr/obj/usr/src/sys/GENERIC  amd64
>>>>>> 
>>>>>> This version still works fine. The one that didn?t work was r270097. The kernel boots but gets stuck at the line:
>>>>>> 
>>>>>> Trying to mount root from zfs:pool/ROOT/default []
>>>>>> 
>>>>>> I tried pressing enter at this point but got a panic, I don?t have a screenshot of the panic at the moment.
>>>>>> 
>>>>>> Could this problem be related the this commit? :
>>>>>> 
>>>>>> http://svnweb.freebsd.org/base?view=revision&sortby=rev&sortdir=down&revision=270095
>>>>>> 
>>>>>> -Kimmo
>>>>> 
>>>>> Trying to bisect this I backed to r270050 and that version still works. More to come.
>>>>> 
>>>>> -Kimmo
>>>> 
>>>> Version r270094 still works but commit r270095 definitely does break booting from ZFS on root on my system. The error message I see on the console is  ?Mounting from <the ZFS filesystem> failed with error 5? and I?m given the mountroot prompt. I don?t see the ZFS pool among the listed GEOM devices on the mountroot prompt.
>>>> 
>>>> Adding the committer of r270095 (kib@) to this discussion.
>>> 
>>> I have no idea about ZFS, but the fact that things, which are lower-level
>>> than ZFS filesystem itself are missing, suggests that the issue is unrelated.
>>> At the very least, start with providing the verbose boot dmesg for successful
>>> and failed boots.
>> 
>> This looks like to be unrelated to ZFS as you?re saying. I just remembered that I?m loading fuse.ko in my /boot/loader.conf. I commented that one out and what do you know? The system boots fine with the r270095 kernel.
>> 
>> Very very strange? 
> This probably indicates KBI mismatch.
> 
> Is your fuse.ko installed from the kernel build ?
> Still, I think the verbose dmesg is the start to look.
> 

The fuse.ko module is from the kernel build because this is on stable/10, the module loads and works if loaded manually after boot and doesn’t seem to affect anything. I don’t yet have an easy way to provide the verbose boot log from a failed boot because this is on real hardware and hooking up a serial console takes some work. I did take a close look on the messages when I booted with 'boot -v' with the fuse.ko included but I didn’t spot anything out of the ordinary.

-Kimmo
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