On Thu, Jun 15, 2006 at 10:05:10AM -0400, Robert Dewar wrote: > You don't need to undo side effects for debugging purposes, you just > need to be able to recreate previous states from the point of view > of the application. So for I/O operations, you need to restore memory > to the state before the I/O operation, but you don't have to try to > somehow undo the external effects of the program, so I don't call that > a restriction at all.
Not really. If you want to be able to back up and try things differently, you need to be able to at least change file seek offsets. Fortunately GDB has code to do this nowadays! It can create "checkpoints" and go back to them later. It doesn't have an actual reverse debugging implementation yet - but it's been proposed. > The point of going backwards (a feature quite familiar to me from > the use of hardware debuggers on PC's in bygone years) is to figure > out what went wrong, and for that purpose you only need to worry > about the machine/memory state. Not when you're debugging userspace and you have files. -- Daniel Jacobowitz CodeSourcery
