Re: [Qemu-devel] [PATCH v4 00/20] instrument: Add basic event instrumentation

[Markus Armbruster]

Lluís Vilanova <address@hidden> writes:

> This series adds an API to add instrumentation events.
>
> It also provides additional APIs for:
> * Controlling tracing events
> * Peek/poke guest memory
>
> There's still missing APIs for (can be added in later series?):
> * Provide something like tracing's per-vCPU trace states (i.e., so that each
>   vCPU can have different instrumentation code). It's still not clear to me if
>   we should extend the per-vCPU bitmap with instrumentation events, or 
> otherwise
>   somehow reuse the bits in tracing events (since they're currently limited).
> * Peek/poke guest registers
>
> The instrumentation code is dynamically loaded as a library into QEMU either
> when it starts or later using its remote control interfaces.
>
> Signed-off-by: Lluís Vilanova <address@hidden>

Taking a step back.

This looks like a way to dynamically load arbitrary code.  What
interfaces can this code use?  Your cover letter should answer this.

As long as the answer is "everything the dynamic linker is willing to
resolve", this series heading nowhere.  We can talk about an interface
for plugins, but "anything goes" is not on the menu.