[cyphar]

> But sure, you need a debugger. So you use one. I'm not sure why the author seems to think that's so hard.

The author wrote and continues to contribute to DTrace, which is an incredibly advanced facility for debugging and root causing problems. GDB (for example) doesn't help you solve performance problems or root-cause them, because now your performance problem has become ptrace (or whatever tracing facility GDB uses on that system).

The point he was making is that there are problems with porting DTrace to a unikernel (it violates the whole "let's remove everything" principle, and you couldn't practically modify what DTrace probes you're using at runtime becuase the only process is your misbehaving app -- good luck getting it to enable the probes you'd like to enable).

[lmm]

You can't modify them from within your app, sure. You modify them from a (privileged) outside context. Allowing the app to instrument itself that thoroughly violates the principle of least privilege the author was so fond of.