Re: Any interest in a QEMU emulation BoF at KVM Forum?

[Alex Bennée]

Alex Bennée <alex.bennee@linaro.org> writes:

qemu-devel keeps bouncing the message so replying with a cut down CC list.

> Hi,
>
> Given our slowly growing range of TCG emulations and the evident
> interest in keeping up with modern processor architectures is it worth
> having an emulation focused BoF at the up-coming KVM Forum?
>
> Some potential topics for discussion I could think of might include:
>
>  * Progress towards heterogeneous vCPU emulation
>
>  We've been making slow progress in removing assumptions from the
>  various front-ends about their global nature and adding accel:TCG
>  abstractions and support for the translator loop. We can already have
>  CPUs from the same architecture family in a model. What else do we need
>  to do so we can have those funky ARM+RiscV+Tricore heterogeneous
>  models? Is it library or something else?
>
>  * External Device Models
>
>  I know this is a contentious topic given the potential for GPL
>  end-runs. However there are also good arguments for enabling the
>  testing of open source designs without having forcing the
>  implementation of a separate C model to test software. For example if
>  we hypothetically modelled a Pi Pico would it make sense to model the
>  PIO in C if we could just compile the Verilog for it into a SystemC
>  model? Would a plethora of closed device models be the inevitable
>  consequence of such an approach? Would it matter if we just
>  concentrated on supporting useful open source solutions?
>
>  * Dynamic Machine Models
>
>  While we try and avoid modelling bespoke virtual HW in QEMU
>  (virt/goldfish not withstanding ;-) there is obviously a desire in the
>  EDA space to allow such experimentation. Is this something we can
>  provide so aspiring HW engineers can experiment with system
>  architectures without having to form QEMU and learn QOM. There have
>  been suggestions about consuming device trees or maybe translating to
>  QMP calls and adding support for wiring devices together. Given the
>  number of forks that exist is this something that could be better
>  supported upstream without degenerating into messy hacks?
>
>  * A sense of time
>
>  Currently we have the fairly limited support for -icount in QEMU. At
>  the same time we have no desire to start expanding frontends with
>  the details cost models required for a more realistic sense of time to
>  be presented. One suggestion is to expand the TCG plugin interface to
>  allow for the plugin to control time allowing as much or little logic
>  to be pushed there as we like and freeing up frontends from ever having
>  to consider it.
>
> Are any of these topics of interest? Are there any other emulation
> topics people would like to discuss?


-- 
Alex Bennée