On Friday, September 19, 2003, at 04:56 AM, Christos Zoulas wrote:
From an API perspective, it is nice if ptrace was more consistentacross 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@localhost>