linux-kernel - Re: [PATCH v6 02/20] liveupdate: luo

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Message-ID: <20251118232517.GD120075@nvidia.com>
Date: Tue, 18 Nov 2025 19:25:17 -0400
From: Jason Gunthorpe <jgg@...dia.com>
To: Pasha Tatashin <pasha.tatashin@...een.com>
Cc: Mike Rapoport <rppt@...nel.org>, pratyush@...nel.org,
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Subject: Re: [PATCH v6 02/20] liveupdate: luo_core: integrate with KHO

On Tue, Nov 18, 2025 at 05:07:15PM -0500, Pasha Tatashin wrote:

> In this case, we cannot even rely on having "safe" memory, i.e. this
> scratch only boot to preserve dmesg/core etc, this is unfortunate. Is
> there a way to avoid defaulting to identify mode when we are booting
> into the "maintenance" mode?

Maybe one could be created?

It's tricky though because you also really want to block drivers from
using the iommu if you don't know they are quieted and you can't do
that without parsing the KHO data, which you can't do because it
doesn't understand it..

IDK, I think the "maintenance" mode is something that is probably best
effort and shouldn't be relied on. It will work if the iommu data is
restored or other lucky conditions hit, so it is not useless, but it
is certainly not robust or guaranteed.

You are better to squirt a panic message out of the serial port and
hope for the best I guess.

Jason