[ECOS] Re: strange behavior with single thread [FIXED]

Karim Naqvi naqvik@uregina.ca
Mon Aug 3 14:28:00 GMT 2009


Mandeep Sandhu wrote:
> False alarm people.
>
> My Makefile was screwed up! I had the .cc target defined (copy-paste
> error)...because
> of which it was using "CC" to compile my program and using i386-elf to link it.
>
> I guess this explains the weired behavior!
>
> Sorry if I wasted anybody's time! :P
>
> Thanks,
> -mandeep
>
> On Mon, Aug 3, 2009 at 4:42 PM, Mandeep
> Sandhu<mandeepsandhu.chd@gmail.com> wrote:
>   
>> Just to add to the rest of the info, I'm using i386-elf (that comes
>> with ecos) to compile my
>> program.
>>
>> I have another program that too has a single thread and it uses TWO
>> struct sockaddr_in var's.
>> That program works just fine!
>>
>> Running strace on the prog shows a lot of Seg faults happening. I'm
>> pretty clueless right now
>> as to why one works while the other does not! :(
>>
>> -mandeep
>>
>> On Mon, Aug 3, 2009 at 2:53 PM, Mandeep
>> Sandhu<mandeepsandhu.chd@gmail.com> wrote:
>>     
>>> Hi All,
>>>
>>> I have a _very_ simple thread app which I've modified from the
>>> "twothreads.c" example.
>>>
>>> It does nothing except start a thread in which I simply print a debug
>>> message and declare
>>> a var of "struct sockaddr_in". But on starting the app, it stops after a call to
>>> cyg_thread_resume(), i.e the thread does not start!
>>>
>>> I had originally written a limited DHCP server implementation (which
>>> was not working)!
>>> So on debugging I narrowed down the problem to a declaration of
>>> "struct sockaddr_in"
>>> variable.
>>>
>>> So I thought I'd make a simple thread which just declares this var and
>>> does nothing. And
>>> even in this sample app (test.c) I saw the same problem. I've
>>> allocated a big enough stack
>>> for the thread - 4KB. Also, increasing the stack size does not help.
>>> The source is pasted
>>> below.
>>>
>>> I know this is only some minor oversight from my side, but any
>>> pointers will be very helpful
>>>
>>> Thanks,
>>> -mandeep
>>>
>>> test.c:
>>>
>>> #include <cyg/kernel/kapi.h>
>>> #include <network.h>
>>>
>>> cyg_thread test_s;
>>> cyg_handle_t test_thread;
>>> cyg_thread_entry_t test_start;
>>> char stack[4096];
>>>
>>>
>>> void test_start(cyg_addrword_t data)
>>> {
>>>    diag_printf("TEST!\n");
>>>    struct sockaddr_in addr;
>>>    cyg_test_exit();
>>> }
>>>
>>> void cyg_user_start(void)
>>> {
>>>    diag_printf("Configuring test thread...\n");
>>>    cyg_thread_create( 4,
>>>                       test_start,
>>>                       (cyg_addrword_t) 0,
>>>                       "TEST Thread",
>>>                       (void *) &stack,
>>>                       4096,
>>>                       &test_thread,
>>>                       &test_s );
>>>
>>>
>>>    diag_printf("Starting test...\n");
>>>    cyg_thread_resume(test_thread);
>>> }
>>>
>>>       
>
>   
Yes, I too ran into that problem, and floundered until I realized that 
cyg_user_start *must* be a "C" symbol as it's called from C code.

-karim


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