Linux emulation instability

[Doug Barton]

Alexander Leidinger wrote:
> Quoting Doug Barton <dougb at FreeBSD.org> (from Mon, 05 Mar 2007 16:05:29 
> -0800):
> 
>> compat.linux.osrelease: 2.4.2
>>
>> Based on your description, and the fact that you're running with
>> ULE+libthr but with UP, I'd be pretty comfortable saying an SMP problem
>> is "likely" at this point. If someone wants to come up with some
>> patches that will likely help the futex+SMP problem, I'll be glad to
>> test them. Otherwise further testing on my part will have to wait till
>> I get some more spare cycles.
> 
> I would be surprised if 2.6.x features like futexes are used with 2.4.2. 
> We don't disable futexes with 2.4.2, but some 2.6.x features are 
> disabled and the glibc of linux_base-fc4 doesn't switch to using 2.6.x 
> features when osrelease is set to 2.4.2. Additionally futexes are not 
> fully implemented on amd64 (at least not in HEAD).
> 
> Also you should not focus on libthr, as it is not used for linux stuff.

Thanks for clearing that up. Would switching to a different linux_base 
port, and/or setting compat.linux.osrelease to something else be a 
useful exercise? This is thunderbird 2.0b2, so it may be expecting 2.6 
stuff that we're not giving it, which may be why it's crashing.

> It would be interesting to know where linux-thunderbird locks up. With a 
> ktrace and maybe the output of linuxulator debugging messages we may be 
> able to narrow this down to the real problem.

Ok, ktrace I can handle, what kind of debugging needs to be set for 
the linuxulator?

> At this point I'm not 100% convinced it is a linux problem per se.

It's 100% reproducible with the combination of 
ULE+SMP+linux-thunderbird. OTOH, I did pretty extensive testing 
without ULE (still running fine that way now, btw), and with ULE but 
without using linux-thunderbird, and it was fine. I will buy that the 
linux-thunderbird code might be doing something it shouldn't, but we 
shouldn't reboot or freeze because of it in any case.

Doug

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