On Wed, May 28, 2008 at 10:09 AM, Gabe Black <[EMAIL PROTECTED]> wrote:
> I've always remembered it as the simulator panicking when something
> unexpected happens, definitely not including user error, and fatal is the
> other one.
Yea, I think of "fatal error" as "fatal user error", while "panic"
implies "this should never happen".
> I almost always use panic because I don't deal with user input
> and configuration that much, although putting in more of that is part of
> what I'll be doing before pushing my x86 stuff. I don't like to use fatal
> because it makes figuring things out in gdb harder. I don't remember exactly
> why, but panic stops gdb immediately and fatal finishes out the program and
> quits which makes it a lot harder to examine what actually happened. I don't
> remember the specifics of any time that was a problem since I think it was a
> while ago, but if there are more detailed messages from fatal it might not
> be as big of an issue.
That's intentional, and I hope makes sense when you think about the
different purposes. If you used fatal, then you should know why you
have a problem (you're just validating that the world is sane), and
you shouldn't have to debug m5 to figure out what it is. panic is the
opposite.
>
> As far as the links to the wiki, I think some form of that would be a good
> idea. The message should be descriptive, but if there was a page with a
> somewhat detailed description of what m5 is complaining about, why it might
> have happened, and some things to try to fix it (not it for writing all
> that), that would probably help people a lot.
I agree... the recent email that kicked this off is a good example.
The error message could be better ("Uninitialized statistic", if
that's what it was), but a link to the wiki page describing how and
why statistics are initialized is still very helpful.
Steve
>
> Gabe
>
> Ali Saidi wrote:
>>
>> On May 28, 2008, at 11:23 AM, nathan binkert wrote:
>>
>>>> panic() -- An assert that isn't compiled out
>>>> fatal() -- some configuration parameter caused a problem
>>>
>>> Ok, I thought so. Do we want to keep these names? I will promise
>>> that I have learned finally, but the names seem a bit to synonymous to
>>> me. I will go through my code and convert the proper things to fatal
>>> since I am at fault for not doing this correctly. Does everyone else
>>> seem to do this stuff correctly, or should we go through more of them?
>>
>> I just learned them and they make sense to me.
>>
>>>
>>> I would also like to add an option to allow panic and fatal (or
>>> whatever their replacements) to raise exceptions into the python so we
>>> can get a stack trace. I don't know if this influences any thoughts
>>> on this.
>>
>> I spent some time trying to do this, if you remember.I never got it to
>> work correctly from inside of m5, but perhaps someone else would have better
>> luck.
>>
>>>
>>>
>>>> Can't we make the error messages themselves descriptive, rather than
>>>> requiring a two step process?
>>>
>>> Well, something like the stat check error needs more description, and
>>> a link to the wiki page would be useful. We could do it only for the
>>> error messages that are necessary of course, but it seems that some of
>>> the error messages should have a lot more information.
>>>
>>>> Most of these errors panic in the c++ and call _exit(). I don't think
>>>> people
>>>> are seeing python error messages that often.
>>>
>>> I think some of the configuration script things could be trapped in
>>> python.
>>
>> I don't know if it's worth spending time adding more indirection to the
>> error path so python can print an error. If the error is fatal python isn't
>> going to be able to correct it and continue.
>>
>> Ali
>>
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