2011/1/11 Chuck Swiger <cswi...@mac.com>:
> On Jan 11, 2011, at 12:11 PM, David DEMELIER wrote:
>> I'm just guessing why current BSD panic() when a problem occurs, all
>> modern operating systems solve the problem instead of crashing
>> suddently and corrupting all your data without saving your work.
>
> You've got it backwards.  A system panic()s to avoid writing corrupted data 
> to disk.
>
>> Yes, why this function exists? There is no way to solve a problem
>> without panic'ing? Is panic really needed?
>
> Sometimes, yes.  If it was possible for the kernel to handle an error 
> condition without panic()ing, then that is obviously preferred-- but there 
> are situations where there is no way for the system to recover.  Common 
> examples of that include when the boot disk fails or disappears, or when the 
> kernel runs out of memory in a situation where it can't get more free pages 
> available.  Less common is when some kind of kernel invariant is violated, 
> indicating that essential kernel data structures have been corrupted.
>

Well I see, I know that kern.sync_on_panic exists to force a sync on a
panic but because my laptop usually does not core dump so never reboot
my disk are not sync'ed :-( it results in a file system not clean an
that's the thing I really hate.

>> Imagine someone working on something really important and his computer just 
>> panic, his work not
>> saved everybody shout at him in the corporation. He lose his job, his
>> wife, his dog, everything is wrong, just because of a panic() !
>
> I admire your contrived example.  :-)  The data available to me suggests that 
> Solaris boxes on enterprise-grade hardware have the highest uptimes; FreeBSD 
> (and related platforms like NetBSD/OpenBSD/DFly/etc) are next, then MacOS X, 
> then Linux, then Windows.
>
> I expect anything based on Unix to be routinely capable of multi-year 
> uptimes; some carefully chosen Windows boxes can also do that, but the 
> widespread prevalence of security issues requiring reboots on Windows means 
> that I don't usually see Windows boxes with uptimes of greater than a month.
>
>> Seriously, I really hate when I play some music that suddenly the
>> music get stucked in a infinite loop, why ?
>
> Probably a bug in the sound card driver.
>

No no, it was a panic that didn't core dump so I needed to do a hard reboot.

>> I don't know because the panic does not core dump. But after some search I 
>> found that the panic
>> was done because of conky. How the hell conky can panic FreeBSD?  We are in 
>> 2011 ! I think even Window 2000 does not crash on a user-land software.
>
> "think"?  If you don't have experience running Windows 2000 are thus are 
> simply guessing, let me assure you that Win 2000 can and does (or did) panic 
> due to userland software.
>

In fact I like FreeBSD, and I don't expect running anything else. But
I must say that I didnt see windows 2000 crashing on my every boxes I
have before switching to FreeBSD.

I understand everything, corrupts kernel data must not be used. That's
why panic are made to prevent any dangerous things.

-- 
Demelier David
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