Hello,
I have built GDB 4.18 as a Linux based PowerPC cross debugger using the config
line
--host=i686-pc-linux-gnu --target=powerpc-eabi
Here is the output of gdb -v
GNU gdb 4.18
Copyright 1998 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB. Type "show warranty" for details.
This GDB was configured as "--host=i686-pc-linux-gnu --target=powerpc-eabi".
I am very pleased and grateful to have this tool. However I am haing trouble
getting the address of variables in ELF executables. My executables are built
with GCC 2.95.2 built as a cross compiler with the same config line as GDB.
When I try to get the address of a global variable I get zero e.g.:
(gdb) p &G_time
$1 = (uint32*) 0x0
(uint32 is a typedef to unsigned long, the real address is 0x77580)
Now stepping through cross-gdb I found the address value got lost
in function store_address in find_var.c and I was able to hack this
function to give the right value
(gdb) p &G_time
$1 = (uint32*) 0x77580
In store_address there is code which seems to be intended truncate a 64 bit
address to fit into a 32 bit value which is then stored. I changed the call to
store_unsigned_integer to use coerce[0] instead of one and all worked fine. I
can't tell from the code whether the problem is in the config if the code is
mixing up target and host byte order.
I have attached store_address function with MY_HACK to show what I mean
/* Store the literal address "val" into
gdb-local memory pointed to by "addr"
for "len" bytes. */
void
store_address (addr, len, val)
PTR addr;
int len;
LONGEST val;
{
if( TARGET_BYTE_ORDER == BIG_ENDIAN
&& len != sizeof( LONGEST )) {
/* On big-endian machines (e.g., HPPA 2.0, narrow mode)
* just letting this fall through to the call below will
* lead to the wrong bits being stored.
*
* Only the simplest case is fixed here, the others just
* get the old behavior.
*/
if( (len == sizeof( CORE_ADDR ))
&& (sizeof( LONGEST ) == 2 * sizeof( CORE_ADDR ))) {
/* Watch out! The high bits are garbage! */
CORE_ADDR coerce[2];
*(LONGEST*)&coerce = val;
#ifdef MY_HACK
store_unsigned_integer (addr, len, coerce[0] ); /* BIG_ENDIAN code! */
#else /* orignal code */
store_unsigned_integer (addr, len, coerce[1] ); /* BIG_ENDIAN code! */
#endif
return;
}
}
store_unsigned_integer (addr, len, val);
}
Many thanks for a great debugging tool!
Philip O'Carroll
Raidtec Corporation
Little Island,
Cork,
Ireland
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