Subject: Re: CVS commit: src/sys/arch/alpha
To: Christos Zoulas <>
From: Jason Thorpe <>
List: source-changes
Date: 09/19/2003 09:11:31
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 

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 

         -- Jason R. Thorpe <>