Re: Segfault on syscall

Shuveb Hussain wrote:
> On 1/2/07, Florian Delizy <[email protected]> wrote:
>> Shuveb Hussain wrote:
>> > Hi,
>> >
>> >> Well, it's not, but as I said there still is this bug in the syscalls
>> >> thing, and since this is a 'random'  bug, I need as much full 
>> detailed
>> >> bug report (see the wiki :
>> >> 
>> http://howto.x-tend.be/openMosixWiki/index.php/OpenMosix2.6#Bug_Reporting 
>>
>> >>
>> >> ) to solve it faster
>> >
>> > Doesn't seem to be random. I have a simple program that does  a long
>> > loop followed by an exit(). The loop gives me time to initiate
>> > migration. Once the loop completes on remote and does exit(), it hits
>> > a seg fault. I fugured the address of the segfault from the page fault
>> > handler in mm/fault.c, it seems to be coming from the C library pages
>> > that are copied.
>> >
>> > main()
>> > {
>> >    int a,b;
>> >
>> >    for(a=0;a<100000;a++)
>> >        for(b=0;b<100000;b++);
>> >
>> >    // compiler inserts exit() here.
>> > }
>> >
>> > The interesting thing is that this program does not segfault when
>> > compiled with '-static'. This fact confused me, since we are copying
>> > the process memory pages verbatim. Certain system calls always
>> > segfault, like exit(), nanosleep(), etc.
>> >
>> > My setup is 2 QEMUs running the Dec 22 release with TUN/TAP and
>> > etherbridge setup for netwoking between them. The QEMUs are running
>> > Debian Etch. Hope this is a good enough setup for debugging, or do I
>> > need 2 real machines?
>> >
>>
>>
>> Well, it sounds like a problem we had, what arch are you running ?
>>
>
> I'm running QEMU 0.8.0 and OpenMosix 2.6.17 with the Dec 22 patch.
> Arch is x86(32 bit).
>
ok, well, I'll try to check the 32bit part, I guess the problem only 
occurs on 32bit arch, since the primary development platform is x86_64 
(and I am not paid to work on 32bit ;) so I have to do it on my week 
ends ...)

i'll let you informed when I get to it ...

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