Problems with Sun4 alignment

[Michael White <mwhite at ftw dot mot dot com>]

Hi all,

   I'm having a problem with the executable generated by gcc 2.8.1 for Sun
4 (uname -a: SunOS drywall3 4.1.3_U1 2 sun4m).  Specifically, I've
specified the following flags/defines in tm.h:

#define STRICT_ALIGNMENT 1
#define STRUCTURE_SIZE_BOUNDARY 32

Here's the structure I'm having problems with:

typedef struct
{
    UBYTE hdr_ver:4;
    UBYTE data_ver:4;
    UBYTE reserved:4;
    UBYTE chan_id:4;
    UWORD len;
    UWORD msg_type;
    STD_SCAP_ADDR dest_addr;
    UWORD resp_type;
    XC_SCAP_ADDR src_addr;
}   SCAP_HDR;

Where:

#define UBYTE   unsigned char
#define UWORD   unsigned short
#define ULONG   unsigned long

typedef struct
{
    UBYTE system;
    UBYTE sub_system[2];
    UBYTE group;
    UBYTE device;
    UBYTE element;
}   STD_SCAP_ADDR;

typedef struct
{
    UBYTE system;
    UBYTE sub_system;
    UBYTE device;
    UBYTE id_1;
    UBYTE id_2;
    UBYTE id_3;
}   XC_SCAP_ADDR;


And finally, here's the line that causes a bus fault (SIGBUS):

i = *(UWORD *)outgoing_scap_msg->scap_hdr.dest_addr.sub_system;

The value of outgoing_scap_msg is 0x3fa89c
The value of &outgoing_scap_msg->scap_hdr.dest_addr is 0x3fa8a4
The value of &outgoing_scap_msg->scap_hdr.dest_addr.sub_system 0x3fa8a5

Perhaps I'm way off base here, but it seems to me that when gcc was
built, it ignored the STRICT_ALIGNMENT define.  This code works correctly
under "cc" (the native Sun4 compiler).

Any solutions would be greatly appreciated.  Please email me if possible.

Thank you.
---
Michael White, qa1402@ftw.mot.com
Cellular Infrastructure Group
Ft. Worth, Texas    (817)245-6418

P.S.  If this is not the proper place to ask these sort of questions, my
apologies.  If you happen to know the proper place, please tell me and/or
forward my email.