Re: [PATCH v6 02/20] liveupdate: luo_core: integrate with KHO

[Mike Rapoport]

On Mon, Nov 17, 2025 at 11:22:54PM -0500, Pasha Tatashin wrote:
> > You can avoid that complexity if you register the device with a different
> > fops, but that's technicality.
> >
> > Your point about treating the incoming FDT as an underlying resource that
> > failed to initialize makes sense, but nevertheless userspace needs a
> > reliable way to detect it and parsing dmesg is not something we should rely
> > on.
> 
> I see two solutions:
> 
> 1. LUO fails to retrieve the preserved data, the user gets informed by
> not finding /dev/liveupdate, and studying the dmesg for what has
> happened (in reality in fleets version mismatches should not be
> happening, those should be detected in quals).
> 2. Create a zombie device to return some errno on open, and still
> study dmesg to understand what really happened.

User should not study dmesg. We need another solution.
What's wrong with e.g. ioctl()?
 
> I think that 1 is better
> 
> Pasha

-- 
Sincerely yours,
Mike.