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

On Mon, Nov 17, 2025 at 11:22:54PM -0500, Pasha Tatashin wrote:

quoted

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.