topic Re: Bad structure alignment in Operating System - HP-UX

Bad structure alignment

Rohan_7 — Thu, 24 Jun 2004 05:26:36 GMT

Hi

I have a structure
typedef struct ipc_msg {
int msg_size;
char msg_data[1024 * 32];
}ipc_msg;

In a function a local variable of this structure type is declared and used. The function definition looks like:
----------------------------------
int sic_recvmsg(socket_ipc_client *sic, void * msg_data)
{
int ret;
ipc_msg msg;
ret = recv_all(SIC_REC->socket, &msg, 0);
....
----------------------

The problem is that when never I call this function, I get SIGBUS. The last line in coredump is start of function.
When I see the address of 'msg', it gives 0x79739f88. As the sizeof ipc_msg is 32772(32768 + 4), the address is not properly aligned and i guess this is the problem.

Can anybody tell me why this is happening?

I am using gcc 3.3.3 on HP-UX 11.11.

Thanks in advance
Rohan

Re: Bad structure alignment

Mike Stroyan — Thu, 24 Jun 2004 14:38:31 GMT

0x79739f88 is properly aligned.
Look more closely at what code and address
is generating the SIGBUS. There isn't enough information here to tell what is causing the SIGBUS. If I had to make a guess I would expect to see that "SIC_REC->socket" uses the "sic" parameter and that was passed in as a bad pointer.

Re: Bad structure alignment

A. Clay Stephenson — Thu, 24 Jun 2004 14:48:18 GMT

Compile/link this with the debugging data flag enabled (-g?) and no optimization and then let it die and use the debugger to examine the dump and do a stack trace. This should zero in on the problem -- down to the offending source line. There is nothing wrong with your struct per se although you might be hitting a limit on maximum struct size --- but I doubt it. I'm simply not up to speed on gcc because I don't use it.

Re: Bad structure alignment

Rohan_7 — Thu, 24 Jun 2004 23:21:14 GMT

Hi

Thanks a lot for your responses.

It turned out to be a different issue!
Thread was hitting the maximum stack size allowed and hence it was giving the SIGBUS.
After increasing the max allowed thread size, its running properly.

Thanks again.
Rohan