Pagefault - Resulting in SIGSEGV

[Hrishikesh Murali]

Hi,

I was just compiling an application in Minix 3.1.9. While I was doing so, I get error messages printed on my console as shown in the screenshot (attached with this mail).

It says that a due to a page fault that had occured, SIGSEGV was received since the address is invalid, and there is a coredump.

Out of pure curiosity:

1. What could these messages mean?
2. Is this a bug in the Minix kernel, or in the application which I'm compiling?
3. If it's a bug in the kernel, how critical is it?

Sometimes (not all the time), the Minix VM just hangs on receiving these messages.

--
Thanks and Regards,
Hrishikesh Murali

[Erik van der Kouwe]

Hi,

>    1. What could these messages mean?

They mean that the application referenced unmapped memory (90% of the
cases that means it dereferenced a NULL pointer).

>    2. Is this a bug in the Minix kernel, or in the application which I'm
>    compiling?

In the application. There is an error message from VM to compensate
for the lack of coredumps. If it only sent out a SIGSEGV you wouldn't
know where it had happended unless the program itself prints a
stacktrace (which is uncommon because it expects a core dump to be
made).

>    3. If it's a bug in the kernel, how critical is it?

It is not a MINIX bug, it is a feature.

> *Sometimes* *(not all the time)*, the Minix VM just hangs on receiving these
> messages.

That might be a bug. How can you tell VM is hung? I would expect
pretty much the whole system to become hung quickly in that case.

With kind regards,
Erik

[Hrishikesh Murali]

Hi,

On Sat, Apr 23, 2011 at 4:32 PM, Erik van der Kouwe <eri...@gmail.com> wrote:

How can you tell VM is hung?

Sorry, I should've been precise. By Minix VM, I meant the Minix 'Virtual Machine' (the whole Minix system).