Changes to kern.geom.debugflags?
Chris Ross
cross+freebsd at distal.com
Sat Dec 29 20:02:03 UTC 2012
On Dec 27, 2012, at 1:15 PM, Chris Ross <cross+freebsd at distal.com> wrote:
>
> On Dec 27, 2012, at 10:43 AM, Chris Ross wrote:
>>>> FreeBSD/sparc64 ZFS boot block
>> Boot path: /pci at 1c,600000/scsi at 2/disk at 1,0:a
>> Consoles: Open Firmware console
>> ERROR: Last Trap: Division by Zero
>>
>> {1} ok ctrace
>> No saved state
>> {1} ok
>>
>> Anything else you can suggest to get debugging information out of zfsloader?
>
> So, I've started with the tiring process of "printf debugging". I have gotten out of
> the loader code, and can show that it's inside of the call to the zfs devsw dv_init()
> call where it's failing.
Okay. Many many iterations, and I found out where it's crashing. In
sys/boot/zfs/zfsimpl.c, in dnode_read(), the first line of the while loop
is:
uint64_t bn = offset / bsize;
And, bsize is calculated from:
int bsize = dnode->dn_datablkszsec << SPA_MINBLOCKSHIFT;
When running the code, though, I can confirm that bsize is 0 before the divide
is hit, thus causing the divide by zero trap.
I'm going to guess this is a problem with dnode->dn_datablkszsec. Has anything
changed recently in zfs_fmtdev, or more likely zfs_get_root() or objset_get_dnode(),
which is the callchain right before dnode_read() ?
- Chris
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