>> +++ b/tests/tcg/plugins/inject.c > > Could we find a better name?
For sure, maybe "hypercalls.c" since that's really what it's mostly about. >> @@ -0,0 +1,206 @@ >> +/* >> + * Copyright (C) 2024, Rowan Hart <rowanbh...@gmail.com> >> + * >> + * License: GNU GPL, version 2 or later. >> + * See the COPYING file in the top-level directory. >> + */ > > We can add a comment here about what the plugin is doing. Will do! > One challenge with picking a random value, is how to ensure this pattern has > no other meaning for all architectures? I'm not sure we can find a single > pattern of bytes that works for all arch, even though that would be > definitely stylish :). > > In more, it seems that we are reinventing the syscall interface, while we > already have it. But as the current instrumentation only works for user-mode, > having a specific hypercall interface might be worth it for plugins, so > system mode could benefit from it too. > > The work done here could serve later to define a proper interface. I'll see what I can do about this. SIMICS supports many architectures and has a "magic instruction" interface[0] (basically hypercalls) and has these instructions defined per-architecture in a way that at minimum there are 12 values available which work on every architecture the simulator supports. QEMU supports more architectures than SIMICS but I think we could start there and follow a similar approach. [0]: https://intel.github.io/tsffs/simics/simics-user-guide/breakpoints.html#Magic-Breakpoints -Rowan
