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

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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

#94215 — Bug#1148952: linux: enable opt-in Kexec Handover and Live Update Orchestrator

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

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#94217 — Processed: Re: Bug#1148952: linux: enable opt-in Kexec Handover and Live Update Orchestrator

Processing control commands:

> tags -1 + patch
Bug #1148952 [src:linux] linux: enable opt-in Kexec Handover and Live Update Orchestrator
Added tag(s) patch.
> forwarded -1 https://salsa.debian.org/kernel-team/linux/-/merge_requests/1845
Bug #1148952 [src:linux] linux: enable opt-in Kexec Handover and Live Update Orchestrator
Set Bug forwarded-to-address to 'https://salsa.debian.org/kernel-team/linux/-/merge_requests/1845'.

-- 
1148952: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1148952
Debian Bug Tracking System
Contact owner@bugs.debian.org with problems

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#94218

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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