Heads-up: Possible regression between 10.0-RELEASE and 10.1-BETA1 with '/ on ZFS' setup

[Glen Barber]

On Sat, Oct 04, 2014 at 04:03:39PM +0100, Steven Hartland wrote:
> >>On Sat, Oct 04, 2014 at 03:51:39AM +0100, Steven Hartland wrote:
> >>> > This has been a known issue on i386 since the switch to Clang see UPDATING:
> >>> 20121223:
> >>>        After switching to Clang as the default compiler some users of ZFS
> >>>        on i386 systems started to experience stack overflow kernel panics.
> >>>        Please consider using 'options KSTACK_PAGES=4' in such configurations.
> >>> > In my experience your millage may vary but essentially without 4 stack pages
> >>> > all bets are off in terms of stability.
> 
> Oh and just looking at the code kern.kstack_pages is read only so wont have
> any effect, hence you will definitely need to set the kernel option as per
> the UPDATING entry.
> 

Indeed, it is readonly.  I'm building kernel on the test VM, but may
have to get the kernel built somewhere else from a non-ZFS VM, because
the i386 VM with ZFS is unusable.

I'm not familiar with these parts of the kernel internals.  What is the
harm in making KSTACK_PAGES=4 the default in i386 GENERIC ?

Glen

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