[ECOS] function pointer in a thread

[ECOS] function pointer in a thread

[Michele Paselli]

Hi all,

I'm trying to build a small and simple network stack for raw
networking. After investigating a bit the existing stacks (in
particular lwip, which is more simple than the bsd implementation) I
found that in the init phase a new thread is started ("Network
Delivery Thread"). In particular the thread always waits for a
semaphore, which is posted by the dsr every time a packet is received,
and then calls the deliver function. The thread is the same as the
lwip implementatiom, I just added few printf:

//Input thread signalled by DSR calls deliver() on low level drivers
static void raweth_thread(void *arg)
  {
    cyg_netdevtab_entry_t *t;

    for (;;) {
      cyg_semaphore_wait(&delivery);
      for (t = &__RAWDEVTAB__[0]; t != &__RAWDEVTAB_END__; t++) {
        struct eth_drv_sc *sc = (struct eth_drv_sc *)t->device_instance;
        if (sc->state & ETH_DRV_NEEDS_DELIVERY) {
  #if defined(CYGDBG_HAL_DEBUG_GDB_CTRLC_SUPPORT)
         cyg_bool was_ctrlc_int;
 #endif
     sc->state &= ~ETH_DRV_NEEDS_DELIVERY;
 #if defined(CYGDBG_HAL_DEBUG_GDB_CTRLC_SUPPORT)
     diag_printf("int_vector function @ 0x%x, sc @
0x%x\n",sc->funs->int_vector,sc);
     was_ctrlc_int = HAL_CTRLC_CHECK((*sc->funs->int_vector)(sc), (int)sc);
     diag_printf("deliver fucntion @ 0x%x\n",sc->funs->deliver);
     if (!was_ctrlc_int) // Fall through and run normal code
 #endif
       (sc->funs->deliver) (sc);
       }
     }
   }
 }

 When I start the application for the first ethernet packet received I got this:

 int_vector function @ 0x43210, sc @ 0x5a2dc
 deliver fucntion @ 0x431cc

 but when a second packet is received this is what I get:

 int_vector function @ 0x1fff20e5, sc @ 0x5a2dc

 and the program hangs. Who is changing the sc structure? I looked in
the lwip implementation and when the thread is created (in the
function sys_thread_new() ) also some memory is allocated, I tried to
do the same but the result does not change. What am I doing wrong?

Thanks.

Michele

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Re: [ECOS] function pointer in a thread

[Andrew Lunn]

On Mon, Jul 23, 2007 at 03:26:41PM +0200, Michele Paselli wrote:
> Hi all,
>
> I'm trying to build a small and simple network stack for raw
> networking. After investigating a bit the existing stacks (in
> particular lwip, which is more simple than the bsd implementation) I
> found that in the init phase a new thread is started ("Network
> Delivery Thread"). In particular the thread always waits for a
> semaphore, which is posted by the dsr every time a packet is received,
> and then calls the deliver function. The thread is the same as the
> lwip implementatiom, I just added few printf:
>
> //Input thread signalled by DSR calls deliver() on low level drivers
> static void raweth_thread(void *arg)
>  {
>    cyg_netdevtab_entry_t *t;
>
>    for (;;) {
>      cyg_semaphore_wait(&delivery);
>      for (t = &__RAWDEVTAB__[0]; t != &__RAWDEVTAB_END__; t++) {
>        struct eth_drv_sc *sc = (struct eth_drv_sc *)t->device_instance;
>        if (sc->state & ETH_DRV_NEEDS_DELIVERY) {
>  #if defined(CYGDBG_HAL_DEBUG_GDB_CTRLC_SUPPORT)
>         cyg_bool was_ctrlc_int;
> #endif
>     sc->state &= ~ETH_DRV_NEEDS_DELIVERY;
> #if defined(CYGDBG_HAL_DEBUG_GDB_CTRLC_SUPPORT)
>     diag_printf("int_vector function @ 0x%x, sc @
> 0x%x\n",sc->funs->int_vector,sc);
>     was_ctrlc_int = HAL_CTRLC_CHECK((*sc->funs->int_vector)(sc), (int)sc);
>     diag_printf("deliver fucntion @ 0x%x\n",sc->funs->deliver);
>     if (!was_ctrlc_int) // Fall through and run normal code
> #endif
>       (sc->funs->deliver) (sc);
>       }
>     }
>   }
> }
>
> When I start the application for the first ethernet packet received I got 
> this:
>
> int_vector function @ 0x43210, sc @ 0x5a2dc
> deliver fucntion @ 0x431cc
>
> but when a second packet is received this is what I get:
>
> int_vector function @ 0x1fff20e5, sc @ 0x5a2dc

Check to see if HAL_CTRLC_CHECK() changes SC. Is 0x1fff20e5 somewhere
in ROM? Is it inside Redboot?

   Andrew

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