On Friday, September 19, 2003, at 04:56  AM, Christos Zoulas wrote:

>> From an API perspective, it is nice if ptrace was more consistent
> across platforms, and provided expected functionality. Otherwise,
> each client program would have to provide this functionality and
> this does not seem right from a maintainance point of view. What
> is the technical reason that this does not belong in the kernel?
> What if we had two debuggers? Wouldn't we have to dup all the code?

The "consistent API" thing is nonsense ... PT_STEP is specifically 
documented as "not available on all machine architectures" (along with 
PT_{GET,SET}REGS and PT_{GET,SET}FPREGS).

The technical reason is simple: The Alpha hardware does not support 
single-stepping, and thus PT_STEP should not be implemented.  Your 
hypothetical debugger has to implement single-stepping functionality 
anyway, because PT_STEP isn't available for kernel debugging.

Also note that Alpha is not the only platform that does not provide 
PT_STEP.

         -- Jason R. Thorpe <thorpej@wasabisystems.com>