Bug#1148952: linux: enable opt-in Kexec Handover and Live Update Orchestrator

From	Salvatore Bonaccorso <carnil@debian.org>
Newsgroups	linux.debian.bugs.dist, linux.debian.kernel
Subject	Bug#1148952: linux: enable opt-in Kexec Handover and Live Update Orchestrator
Date	2026-09-26 11:10 +0200
Message-ID	<NHwzT-1T43-5@gated-at.bofh.it> (permalink)
References	<NHfSp-1K0V-7@gated-at.bofh.it> <NHfSp-1K0V-7@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Cross-posted to 2 groups.

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Control: tags -1 + patch
Control: forwarded -1 https://salsa.debian.org/kernel-team/linux/-/merge_requests/1845

Hi,

On Fri, Sep 25, 2026 at 05:08:42PM +0200, Artem Prilutskiy wrote:
> Package: src:linux
> Version: 7.2.7-1
> Severity: wishlist
> 
> Please consider enabling the following options in Debian kernel builds on architectures that support them (in particular amd64 and arm64):
> 
> CONFIG_KEXEC_HANDOVER=y
> CONFIG_KEXEC_HANDOVER_ENABLE_DEFAULT=n
> CONFIG_LIVEUPDATE=y
> CONFIG_LIVEUPDATE_MEMFD=y
> 
> The default-off setting is intentional. Kexec Handover should remain
> opt-in through the kho=on kernel parameter; Live Update Orchestrator
> likewise requires liveupdate=on. This makes the facilities available
> without changing the default behavior or requiring users to rebuild
> Debian kernels.
> 
> Our use case is a stateful service that stores application state in
> memfds held by systemd's file descriptor store. That state includes
> many UDP connection contexts. With KHO and LUO, a new kernel and
> service instance can recover the same memfd-backed state across
> kexec. This does not require the kernel to preserve the UDP sockets
> themselves. We have exercised the handover with a custom 7.2.7
> kernel in a Debian sid KVM guest; stock Debian kernels do not
> currently expose these options.
> 
> The options are provided upstream and remain gated by the required
> architecture and feature dependencies. Enabling them in Debian would
> let interested users test and deploy this mechanism explicitly,
> while leaving normal boots unchanged.
> 
> Upstream documentation: https://docs.kernel.org/core-api/liveupdate.html

There is MR to request those additions at
https://salsa.debian.org/kernel-team/linux/-/merge_requests/1845 . So
linking both.

The choice to have it opt-in is likely sensible, should be followed up
on the MR.

Regards,
Salvatore

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Bug#1148952: linux: enable opt-in Kexec Handover and Live Update Orchestrator Artem Prilutskiy <cyanide.burnout@gmail.com> - 2026-09-25 17:20 +0200
  Processed: Re: Bug#1148952: linux: enable opt-in Kexec Handover  and Live Update Orchestrator "Debian Bug Tracking System" <owner@bugs.debian.org> - 2026-09-26 11:10 +0200
  Bug#1148952: linux: enable opt-in Kexec Handover and Live Update Orchestrator Salvatore Bonaccorso <carnil@debian.org> - 2026-09-26 11:10 +0200

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