Messages in this thread | | | Subject | Re: [PATCH v1 0/4] virt: vmgenid: Add devicetree bindings support | From | David Woodhouse <> | Date | Wed, 20 Mar 2024 13:50:43 +0000 |
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On Tue, 2024-03-19 at 16:24 +0100, Krzysztof Kozlowski wrote: > On 19/03/2024 15:32, Sudan Landge wrote: > > This small series of patches aims to add devicetree bindings support for > > the Virtual Machine Generation ID (vmgenid) driver. > > > > Virtual Machine Generation ID driver was introduced in commit af6b54e2b5ba > > ("virt: vmgenid: notify RNG of VM fork and supply generation ID") as an > > ACPI only device. > > We would like to extend vmgenid to support devicetree bindings because: > > 1. A device should not be defined as an ACPI or DT only device. > > Virtual stuff is not a device, so your first assumption or rationale is > not correct. > > Virtual stuff can be ACPI only, because DT is not for Virtual stuff.
I strongly disagree with this.
Discovering things is what the device-tree is *for*.
We don't want to add extra complexity and overhead on both host and guest side to make things discoverable in a *less* efficient way.
The device-tree isn't just a last-resort for when we can't possibly do things differently in a discoverable way. The device-tree is a first- class citizen and perfectly valid choice as a way to discover things.
We shouldn't be forcing people to turn things into PCI devices just to avoid adding DT bindings for them.
And we *certainly* shouldn't be directing people towards all the awfulness of ACPI, and in-kernel bytecode interpreters, and all that horridness, just because we don't want to use DT to... describe things.
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