I know this is ancient news, but the debugger still doesn't work with 
recent kernels (2.6.16-rc3) and I was trying to find out why. Basically, 
the debugger launches a couple of processes that are running all the 
time using 100% cpu time between them. The program that the debugger is 
supposed to be debugging never sees the light of day.

Note: maybe it is Kylix's fault that it is hanging like this. It seems 
to be using LinuxThreads (which is not a very good sign) and by being 
closed source it makes it very hard to find out exactly what's 
happening. The conclusion of this thread might very well be: "the kernel 
is doing the right thing, the Kylix debugger is wrong and it should be 
fixed". This would be fine by me, I just want to be sure this is the 
"official" stance before I give up on this :)

Anyway, by bisecting the kernel versions, I found out that the version 
where the debugger stops working is 2.6.10-bk5. Digging into the patch, 
I was able to isolate even further.

If I apply all the bk4-bk5 patch *except* the patch attached to this 
email, the debugger still works.

Going even further, a 2.6.10-bk5 kernel without this single change runs 
the debugger just fine:

> @@ -718,23 +717,21 @@
>  		 */
>  		if ((regs->xcs & 3) == 0)
>  			goto clear_TF_reenable;
> -		if ((tsk->ptrace & (PT_DTRACE|PT_PTRACED)) == PT_DTRACE)
> -			goto clear_TF;
> +
> +		/*
> +		 * Was the TF flag set by a debugger? If so, clear it now,
> +		 * so that register information is correct.
> +		 */
> +		if (tsk->ptrace & PT_DTRACE) {
> +			regs->eflags &= ~TF_MASK;
> +			tsk->ptrace &= ~PT_DTRACE;
> +			if (!tsk->ptrace & PT_DTRACE)
> +				goto clear_TF;
> +		}
>  	}
>  
>  	/* Ok, finally something we can handle */

I CC'd Linus Torvalds because, from the ChangeLog, he was the one who 
wrote this code, so maybe he can shed some light here.

Anyway, using the awesome magical power of blind "hand patching", I 
tried to revert this from the 2.6.16-rc3 kernel, but my powers have let 
me down this time :(

Alas, the current kernel is very different from the 2.6.10 version and I 
don't understand this code enough to be able to modify it. (I did try it 
anyway, without success: the debugger still hung).

Now, the next step would be to try to progress through the kernel 
versions in smaller steps, testing the debugger along the way, to see 
where it breaks again, and repeat until I reach 2.6.18 (that is probably 
where the kernel will be by the time I finish this process :) ).

Before I start moving in that direction is there someone who can give me 
an hint about what might be happening and suggest patches to test, etc.?

TIA,

-- 
Paulo Marques - www.grupopie.com

Pointy-Haired Boss: I don't see anything that could stand in our way.
            Dilbert: Sanity? Reality? The laws of physics?