Re: [PATCH 1/3] mm: vmalloc: export __vmalloc_node_range

Mary Strodl
2024-07-18T13:20:18Z

On Thu, Jul 18, 2024 at 01:53:23PM +0100, Matthew Wilcox wrote:
> That does work, but I would assume that since this BIOS exists to
> communicate with the hardware that it'd need various special privileges
> and that running in ring 3 would not work.

Exactly.

> Ultimately, better off running the whole thing inside a VM and passing
> the device through to the guest. Or ignoring the BIOS entirely and
> implementing direct access to the hardware. But neither of these
> approaches is "a way to do what I'm trying to do", they're entirely
> different approaches to making this hardware work.

If I ran the whole thing inside a VM, I would still need support in the
kernel, right?

As far as I know, there is no documentation on Congatec's side about the
underlying interface. Obviously I could disassemble the blob in the BIOS
and figure it out, but I suspect that will have much less hardware
compatibility and be subject to random breakage if they make a BIOS
update or something. Plus, I would probably run afoul of copyright if I
wrote a driver after doing that.

I'm not really thrilled that this is their design either, but I'm not
sure that there is a better answer...

Thank you!