RE: [PATCH v4 2/5] x86/hyper-v: Add synthetic debugger definitions

[Michael Kelley <mikelley@microsoft.com>]

From: Vitaly Kuznetsov <vkuznets@redhat.com>  Sent: Thursday, March 12, 2020 6:51 AM
> 
> Michael Kelley <mikelley@microsoft.com> writes:
> 
> > I'm flexible, and trying to not be a pain-in-the-neck. :-)  What would
> > the KVM guys think about putting the definitions in a KVM specific
> > #include file, and clearly marking them as deprecated, mostly
> > undocumented, and used only to support debugging old Windows
> > versions?
> 
> I *think* we should do the following: defines which *are* present in
> TLFS doc (e.g. HV_FEATURE_DEBUG_MSRS_AVAILABLE,
> HV_STATUS_OPERATION_DENIED, ...) go to asm/hyperv-tlfs.h, the rest
> (syndbg) stuff goes to kvm-specific include (I'd suggest we just use
> hyperv.h we already have).
> 
> What do you think?
> 

I could live with this proposal, since they *are* in the TLFS v6.0 as it
exists today. However, v6.0 seems inconsistent in what parts of this
debugging functionality it exposes, probably just because someone
hasn't thought comprehensively about the topic across the whole 
document.   I'll make sure that it gets looked at in the next revision 
(which should be a lot sooner that the 2+ years it took to get the v6.0
revision done).   But I won't be surprised if the remaining vestiges are
removed at that time, in which case we would want to move the
definitions from hyperv-tlfs.h to KVM's hyper.h.

Michael