Re: Difficulties to access guest memory in TCG plugins

[Peter Maydell]

On Fri, 25 Jun 2021 at 10:25, Kevin Mambu <kevin.mambu@pm.me> wrote:
> In the scope of my Ph. D subject, I want to model a DMA-like mechanism for 
> quick prototyping and evaluation, the plugin emulates an MMIO with 
> Control/Status Registers. I am actually able to pass parameters to the 
> Control/Status Registers through store instruction without any issue. Only 
> the data transfer between two guest memory regions fails at times.

This really isn't what the plugin API is intended for -- it's meant
for tracing and similar sorts of "track what the guest is doing" activities.
If you want to model an MMIO device, you're better off just writing a device
model like any of the others in QEMU, I think: the APIs for doing that
are much more well-proven and there's plenty of examples in the tree
of DMA and other devices.

-- PMM