Re: [PATCH 00/23] Subject: [PATCH net-next 00/23] net/hpe: add HPE Slingshot NIC drivers

[Jason Gunthorpe <jgg@ziepe.ca>]

On Wed, Nov 04, 2026 at 03:48:58PM +0100, Andrew Lunn wrote:

> A bit of an aside. Do you have the complete history of the driver?
> What did the first 10 patches do? When bringing up new hardware, you
> start small and get a little piece working. 

If you are implementing a driver from a datasheet, sure.

However a device like this was almost certainly co-designed in a chip
simulator along side the HW and by the time the HW was done they had a
mostly complete driver ready to go. The actual baked chip probably
never ran a driver like you are imagining.

> I'm assuming you did something similar, small bits of code you could
> somehow test. Those small bits of code, step by step development, are
> generally easy to review.

When you are co-designing with a chip simulator things work
differently, you'd focus on the more risky parts of the IP and do
partial driver flows and so on to vet things out. Lots of carefully
orchestrated shortcuts. Then you take that and assemble a complete
driver to run more complete sim passes. As this progresses the HW is
changing underneath and the SW is following along.

So it is completely understandable they ended up with a completed
driver at the end of the process rather than a bunch of logical small
steps.

> Generally, none. We just want a plain, boring netdev, which looks the
> same as every other plain boring netdev in the kernel. OS 101, the OS
> is there to abstract over the hardware so all hardware looks the same.

Yeah, this is a reasonable place to start. I also discourage any uAPI
introduction into any new drivers. Start with the basics then we can
talk about why it needs new uAPI point by point.

Jason