On Wed, Sep 06, 2017 at 20:22:41 +0300, Lluís Vilanova wrote: > This series adds an API to add instrumentation events. > > It also provides additional APIs for: > * Controlling tracing events
hmm didn't Stefan say that tracing should be decoupled from this? > * 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). As I said in the description of my alternative implementation [*], I don't see much value in having per-vCPU events, as most instrumenters just care about the guest application/system. I can only think of cases where the instrumenter is only interested in a guest process (in system-mode), but that'd be ugly anyway (would need to change both QEMU and the guest kernel to track the pid). If the need ever arises, we could add __vcpu(cpu_index) registration functions. [*] https://lists.gnu.org/archive/html/qemu-devel/2017-09/msg01446.html E.
