Re: [virtio-comment] TAB Comments on Virtual I/O Device (VIRTIO) Version 1.0

[Rusty Russell <rusty@au1.ibm.com>]

Patrick Durusau <patrick@durusau.net> writes:
> TAB-556	Conformance targets
> 
> 	After reading 2.2.1 Legacy Interface, again, I have a suggestion
> 	for conformance targets in section 9 (subject to my getting this
> 	wrong): 1. Non-Transitional Device - enumerate which sections of
> 	normative text I MUST conform to in order to have a
> 	Non-Transitional Device. 2. Non-Transitional Driver - enumerate
> 	which sections of normative text I MUST conform to in order to
> 	have a Non-Transitional Driver. 3. #1 plus ?? = Transitional
> 	Device. 4. #2 plus ?? = Transitional Driver with the
> 	sub-numbering under 1 - 4 specifying the details of
> 	conformance. Yes?

I originally wanted to make all the legacy sections non-normative, and
thus avoid any MUSTs in there.  It's a bit weird, becuase legacy systems
our outside the scope of the current standard, but we really do want to
be kind for people in transition.

I think Michael had objections to this, though.  So here's my
compromise:

diff --git a/conformance.tex b/conformance.tex
index 0e8b321..d564392 100644
--- a/conformance.tex
+++ b/conformance.tex
@@ -6,3 +6,54 @@
 An implementation conforms to this specification if it satisfies
 all of the MUST or REQUIRED level requirements defined within
 this specification.
+
+In particular, a device does not need to support legacy drivers, nor
+a driver support legacy devices to confirm to this specification,
+ie. non-transitional drivers and devices are fine.  (In fact, the only
+awareness such non-transitional implementations need that legacy
+systems ever existed is specified in \ref{sec:Virtio Transport Options / Virtio Over PCI Bus / PCI-specific Initialization And Device Operation / Device Initialization / Non-transitional Device With Legacy Driver}
+for PCI device implementations).
+
+All requirements for such transitional devices and drivers are
+explicitly noted as such, and contained within sections named ``Legacy
+Interfaces''.  These sections also function to assuage the guilt of
+the committee for breaking existing deployments:
+
+\begin{itemize}
+\item Section \ref{sec:Basic Facilities of a Virtio Device / Feature Bits / Legacy Interface: A Note on transitions from earlier drafts}
+\item Section \ref{sec:Basic Facilities of a Virtio Device / Device Configuration Space / Legacy Interface: A Note on Configuration Space endian-ness}
+\item Section \ref{sec:Basic Facilities of a Virtio Device / Device Configuration Space / Legacy Interface: Device Configuration Space}
+\item Section \ref{sec:Basic Facilities of a Virtio Device / Virtqueues / Legacy Interfaces: A Note on Virtqueue Layout}
+\item Section \ref{sec:Basic Facilities of a Virtio Device / Virtqueues / Legacy Interfaces: A Note on Virtqueue Endianness}
+\item Section \ref{sec:Basic Facilities of a Virtio Device / Virtqueues / Message Framing / Legacy Interface: Message Framing}
+\item Section \ref{sec:General Initialization And Device Operation / Device Initialization / Legacy Interface: Device Initialization}
+\item Section \ref{sec:Virtio Transport Options / Virtio Over PCI Bus / PCI Device Discovery / Legacy Interfaces: A Note on PCI Device Discovery}
+\item Section \ref{sec:Virtio Transport Options / Virtio Over PCI Bus / PCI Device Layout / Legacy Interfaces: A Note on PCI Device Layout}
+\item Section \ref{sec:Virtio Transport Options / Virtio Over PCI Bus / PCI-specific Initialization And Device Operation / Device Initialization / Virtio Device Configuration Layout Detection / Legacy Interface: A Note on Device Layout Detection}
+\item Section \ref{sec:Virtio Transport Options / Virtio Over PCI Bus / PCI-specific Initialization And Device Operation / Device Initialization / Virtqueue Configuration / Legacy Interface: A Note on Virtqueue Configuration}
+\item Section \ref{sec:Virtio Transport Options / Virtio Over MMIO / Legacy interface}
+\item Section \ref{sec:Virtio Transport Options / Virtio over channel I/O / Device Initialization / Setting the Virtio Revision / Legacy Interfaces: A Note on Setting the Virtio Revision}
+\item Section \ref{sec:Virtio Transport Options / Virtio over channel I/O / Device Initialization / Configuring a Virtqueue / Legacy Interface: A Note on Configuring a Virtqueue}
+\item Section \ref{sec:Virtio Transport Options / Virtio over channel I/O / Device Operation / Host->Guest Notification / Legacy Interfaces: A Note on Host->Guest Notification}
+\item Section \ref{sec:Virtio Transport Options / Virtio over channel I/O / Device Initialization / Setting Up Indicators / Legacy Interfaces: A Note on Setting Up Indicators}
+\item Section \ref{sec:Device Types / Network Device / Feature bits / Legacy Interface: Feature bits}
+\item Section \ref{sec:Device Types / Network Device / Device configuration layout / Legacy Interface: Device configuration layout}
+\item Section \ref{sec:Device Types / Network Device / Device Operation / Legacy Interface: Device Operation}
+\item Section \ref{sec:Device Types / Network Device / Device Operation / Control Virtqueue / Setting MAC Address Filtering / Legacy Interface: Setting MAC Address Filtering}
+\item Section \ref{sec:Device Types / Network Device / Device Operation / Control Virtqueue / VLAN Filtering / Legacy Interface: VLAN Filtering}
+\item Section \ref{sec:Device Types / Network Device / Device Operation / Control Virtqueue / Automatic receive steering in multiqueue mode / Legacy Interface: Automatic receive steering in multiqueue mode}
+\item Section \ref{sec:Device Types / Network Device / Device Operation / Control Virtqueue / Offloads State Configuration / Setting Offloads State / Legacy Interface: Setting Offloads State}
+\item Section \ref{sec:Device Types / Block Device / Feature bits / Legacy Interface: Feature bits}
+\item Section \ref{sec:Device Types / Block Device / Feature bits / Device configuration layout / Legacy Interface: Device configuration layout}
+\item Section \ref{sec:Device Types / Block Device / Device Initialization / Legacy Interface: Device Initialization}
+\item Section \ref{sec:Device Types / Block Device / Device Operation / Legacy Interface: Device Operation}
+\item Section \ref{sec:Device Types / Console Device / Device configuration layout / Legacy Interface: Device configuration layout}
+\item Section \ref{sec:Device Types / Console Device / Device Operation / Legacy Interface: Device Operation}
+\item Section \ref{sec:Device Types / Memory Balloon Device / Device configuration layout / Legacy Interface: Device configuration layout}
+\item Section \ref{sec:Device Types / Memory Balloon Device / Device Operation / Memory Statistics / Legacy Interface: Memory Statistics}
+\item Section \ref{sec:Device Types / SCSI Host Device / Device configuration layout / Legacy Interface: Device configuration layout}
+\item Section \ref{sec:Device Types / SCSI Host Device / Device Operation / Device Operation: Request Queues / Legacy Interface: Device Operation: Request Queues}
+\item Section \ref{sec:Device Types / SCSI Host Device / Device Operation / Device Operation: controlq / Legacy Interface: Device Operation: controlq}
+\item Section \ref{sec:Device Types / SCSI Host Device / Device Operation / Device Operation: eventq / Legacy Interface: Device Operation: eventq}
+\item Section \ref{sec:Reserved Feature Bits / Legacy Interface: Reserved Feature Bits}
+\end{itemize}