ptrace and FP math on x86

Martin von Loewis (martin@mira.isdn.cs.tu-berlin.de)
Thu, 29 Jan 1998 08:17:11 +0100

Since a new release of gdb is being prepared, maybe this is the time
to get a debugger that also knows about the floating point processor
of the 486 or better processors.

Unfortunately, it seems that 2.0 and 2.1 have diverged in the
ptrace interface: where 2.0.33 allows PEEKUSR and POKEUSR to access
the FP registers, 2.1.82 has GETFPREGS and SETFPREGS. (One historical
note: when 2.0 was initially released, there was no way for a debugger
to find out what the FPU state is).

I'm not arguing that one interface is better than the other. I only
want to know which one is going to be the official interface. If both,
I wonder whether gdb could support them both, and whether anybody is
working on that gdb support. I know there is a gdb patch for the 2.0
interface (by Ramon Garcia).

In any case, I think we'll have to act quickly. The gdb 4.17 release
is imminent. If we miss this, the next gdb release might well be in
the next century, given that 4.16 was released in early 1996.

Thanks,
Martin