[Vm-dev] Re: Cog on Linux
Eliot Miranda
eliot.miranda at gmail.com
Thu Jul 22 21:44:11 UTC 2010
Hi Derek,
On Thu, Jul 22, 2010 at 2:25 PM, Derek O'Connell <doconnel at gmail.com> wrote:
>
> On 22/07/10 22:20, Eliot Miranda wrote:
>
>>
>>
>>
>>
>> Hi Paul,
>>
>> On Thu, Jul 22, 2010 at 2:14 PM, Paul DeBruicker<pdebruic at gmail.com>
>> wrote:
>>
>>
>>> Hi Eliot,
>>>
>>>
>>>
>>> On 07/22/2010 05:02 PM, vm-dev-request at lists.squeakfoundation.org wrote:
>>>
>>> handle SIGUSR2 nostop noprint noignore
>>>>
>>>>
>>>> If I include the above line in my .gdbinit then gdb complains:
>>>
>>> Cannot find user-level thread for LWP XXXXX
>>>
>>> where XXXXX is the process number for the VM. Sometimes the VM window
>>> stays open and freezes at that point and sometimes it closes. Gdb then
>>> states that the "Target is running" when I type in the commands you
>>> listed.
>>> If I comment the "handle SIGUSR2 ..." line out then I get this from
>>> those
>>> commands:
>>>
>>>
>> just looks like the OS/run-time is not letting the program set a handler
>> for
>> SIGUSR2 and/or not allowing it to be caught. This is a deal breaker. Why
>> it's happening I don't know, but currently Cog's heartbeat on linux
>> depends
>> on being able to catch SIGUSR2.
>>
>
> From: http://pauillac.inria.fr/~xleroy/linuxthreads/faq.html
>
> H.4: With LinuxThreads, I can no longer use the signals SIGUSR1 and SIGUSR2
> in my programs! Why?
>
> The short answer is: because the Linux kernel you're using does not support
> realtime signals.
>
I'd forgotten all that! I thought that stuff was ancient history. So we
need two things, one is a pair of alternative signals, the other is a
reliable #define that we can use to distinguish l'ancien regime from the
modern day.
thanks Derek!
best
Eliot
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