[PVE-User] Hardcoded startup RAM for QEMU memory hotplug

[PVE-User] Hardcoded startup RAM for QEMU memory hotplug

[Jan Pechek via pve-user]

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From: Jan Pechek <jan.pechek@daktela.com>
To: pve-user@lists.proxmox.com
Subject: Hardcoded startup RAM for QEMU memory hotplug
Date: Thu, 8 Jan 2026 14:43:34 +0100
Message-ID: <CAHQqQDa-z-vEdrE1Fpt1F6BsqSsxcqpECfFhb=L=ssviMn+eOQ@mail.gmail.com>

Hello,
I would like to ask if it is possible to have the startup RAM size for
memory hotplug configurable.
We encountered a problem when upgrading Alma9 to Alma10 using the
leapp (https://leapp-repository.readthedocs.io/latest/) tool. It
creates a modified initramfs in which it performs the operating system
upgrade. However, because it is in the early boot stage of the system,
the automatic connection of hotpluggable memory does not work and only
1024MB of startup RAM is available. So leapp does not have enough
memory and OOM killer terminates it.
If we patch this hardcoded value
(https://github.com/proxmox/qemu-server/blob/e781d9713fb3d45a523fe14db6cd99ac60bbfbb5/src/PVE/QemuServer/Memory.pm#L66)
and increase the startup RAM to 2048MB, for example, everything will
work fine.
For current RHEL, the minimum required memory is 2GB as is stated here
- https://access.redhat.com/articles/rhel-limits#minimum-required-memory-3.
Please also see this related issue -
https://bugzilla.redhat.com/show_bug.cgi?id=2139907.

If there is better way to create feature request, please let me know, thanks.



Best regards,

Jan Pechek


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Re: [PVE-User] Hardcoded startup RAM for QEMU memory hotplug

[DERUMIER, Alexandre via pve-user]

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From: "DERUMIER, Alexandre" <alexandre.derumier@groupe-cyllene.com>
To: "pve-user@lists.proxmox.com" <pve-user@lists.proxmox.com>
Subject: Re: [PVE-User] Hardcoded startup RAM for QEMU memory hotplug
Date: Thu, 8 Jan 2026 15:21:01 +0000
Message-ID: <1b5536bef426ee07ef087fc76ec1a7ca196a5afa.camel@groupe-cyllene.com>

hi currently no, but it's related to the number of cpu sockets of the
vm. (it's 512mb by socket if I remember correctly).

so, you can try a vm with 4 sockets.


you can also add "memhp_default_state=online" to kernel boot option, it
should auto enable the hotplug memory dimm when kernel boot


-------- Message initial --------
De: Jan Pechek via pve-user <pve-user@lists.proxmox.com>
Répondre à: Proxmox VE user list <pve-user@lists.proxmox.com>
À: pve-user@lists.proxmox.com
Cc: Jan Pechek <jan.pechek@daktela.com>
Objet: [PVE-User] Hardcoded startup RAM for QEMU memory hotplug
Date: 08/01/2026 14:43:34

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