Hi,

Bug 567 complains that when you build gdb for sparc-sun-solaris2.8 as a 64-bit
program, then when you use it to debug a 32-bit program things happen like:

   (gdb) p d1
   Cannot access memory at address 0xffbef7a0
   (gdb) x/fg &d1
   0xffbef7a0:     3.2999999999999998

(Actually 567 shows the wrong value being printed to x/fg, but this seems to be
fixed at gcc-3.2 / gdb 5.2.1).

It turns out that you can't "p" any kind of variable: the problem isn't limited
to double.

The problem seemed to me that 32-bit negative stack offsets became +ve 64-bit
quantities. This would give a 33-bit address (the wanted address with an extra
"1" on the left).

Ideally, I think gdb should just mask off the extra bit when debugging 32-bit
code. But I couldn't figure out how to do that, so the attached patch
sign-extends symbol values as they are read in.

GCC 3.2 configuration:

 /tmp/gcc-3.2/configure --prefix=/usr/local/gcc-3.2

GDB 5.2.1 configuration

 PATH=/usr/local/gcc-3.2/bin:$PATH
 export PATH
 CC="gcc -m64"
 export CC
 CFLAGS="-g -O2"
 export CFLAGS
 ./configure --prefix=/usr/local/solaris2.8_64

You need to put "-m64" in CC rather than CFLAGS else "make install" fails when
trying to build "chew". This has the unfortunate side-effect that "make check"
also uses "gcc -m64", i.e. it never exercises "gcc" which would build a 32-bit
program.

Cheers ... Duncan.