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From: Wolfgang Bumiller <w.bumiller@proxmox.com>
To: Constantin Herold <proxmox8914@herold.me>
Cc: pve-devel@lists.proxmox.com
Subject: Re: [pve-devel] [PATCH qemu-server] fix #3581: pass size via argument for memory-backend-ram qmp call
Date: Wed, 18 Aug 2021 08:54:22 +0200	[thread overview]
Message-ID: <20210818065422.rynkx5eovz6alsay@olga.proxmox.com> (raw)
In-Reply-To: <a382c4cf-d38c-ca64-4480-ba958aa7aded@herold.me>

On Tue, Aug 17, 2021 at 05:32:00PM +0200, Constantin Herold wrote:
> Sure no problem.
> 
> In that case the patch will probably break memory hotplug for any VM's
> tagged to Qemu <=4.2

I think it's okay as it's just the command interface to the running qemu
process.

* pve6 has qemu 5.2 (supports both variants)
* pve7 has qemu 6.0 (supports only the new one)

For clusters we recommend migrating running machines to different nodes
when upgrading, which means they'll be running on pve6+qemu5.2 and then get
migrated to pve7-qemu6, afterwards hotplug should be working once this
patch lands.

For in-place major-upgrades with machines running this doesn't really
*break* a running machine, just prevents hotplug until it was either
stop-started or a live-snapshot&rollback is performed.

If you want to go the extra mile, the running qemu version could be
queried, but I don't think we need to insist on doing this, as it just
adds code complexity for backward-compatibility across a major-version
boundary.




      reply	other threads:[~2021-08-18  6:54 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-12 18:16 Constantin Herold
2021-08-17 13:21 ` Wolfgang Bumiller
2021-08-17 15:32   ` Constantin Herold
2021-08-18  6:54     ` Wolfgang Bumiller [this message]

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