Re: [PATCH 1/3] virtio: dwords->qwords

Andrew Lunn
2025-10-11T18:52:28Z

> That's not spec, that's linux driver. The spec is the source of truth.

Right, lets follow this.

I'm looking at

https://docs.oasis-open.org/virtio/virtio/v1.3/csd01/virtio-v1.3-csd01.html

Is that correct?

That document does not have a definition of word. However, what is
interesting is section "4.2.2 MMIO Device Register Layout"

DeviceFeaturesSel 0x014

Device (host) features word selection.
Writing to this register selects a set of 32 device feature bits accessible by reading from DeviceFeatures.

and

DriverFeaturesSel 0x024

Activated (guest) features word selection
Writing to this register selects a set of 32 activated feature bits accessible by writing to DriverFeatures.

I would interpret this as meaning a feature word is a u32. Hence a
DWORD is a u64, as the current code uses.

Andrew