RE: [PATCH v2 2/3] LAM: Enable tagged pointer support for watchpoints.

["Willgerodt, Felix" <felix.willgerodt@intel.com>]

> > Or maybe we even want to warn if we find the string but can't convert
> > it to a proper mask.
> 
> As I said before I am not sure how we should handle those error conditions.
> Maybe somebody else can help us here?

I think we want to warn or error out. You can look at existing GDB code.
For example here GDB prints an error if it couldn't read an integer from
a Linux file:
https://sourceware.org/git/?p=binutils-gdb.git;a=blob;f=gdb/nat/linux-btrace.c;h=5715168d2f0887da2321694b5a8f3e21e74c4ad7;hb=8e8b2ab688b3d7e6035e6c782a2b42501d57c667#l601
Not sure if there are other examples or counter examples,
this just one I knew of.

In your case it is very unlikely that this will ever happen yes. But I think
GDB is just much better off to check this. Otherwise the function
might return some wrong mask silently. A warning or error makes it
much easier to understand, if there ever is a bug.

Is the untag_mask string in the file, even if the default mask is "active"?
In that case you could argue a warning is good enough, as we
don't actually know if the watchpoint would be set to a wrong address.

Though to be on the safe side, I lean towards an error.  We have the
indication that LAM is supported (or even active), but can't read the mask.
So we don't know if we can set a watchpoint on the right address.
Yes this prevents users from setting watchpoints, but since it is an unlikely
scenario I hope this is never a real problem for someone.

And note that my code was just a rough sketch, please double check it.

Felix
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