On Thu, Jan 15, 2026 at 12:03:02PM -0000, [email protected]
wrote:
> Hi Peter,
> First of all: Thank you for your very elaborate answer! There’s a lot to
> digest here, and I want to discuss internally with my colleagues how we
> proceed. I’m pretty sure we will reach out again after we thought through
> more of the details.
>
> Peter Krempa wrote:
> > On Mon, Jan 12, 2026 at 14:28:02 -0000,
> > [email protected] wrote:
> > > 2)> If we attach a device `A` with `--live` and a second device `B` with
> > > `--persistent`, then `A` will not be present in the persistent domain
> > > XML. Still, we expect that `B` is added to both live and persistent
> > > definitions, using the same PCI bus address. By doing so, we would
> > No if you use only --persistent you *must not* touch the live config.
> > This is just a cold-plug request.
>
> This is one point I would like to discuss further, nevertheless.
> Your statement leaves me a bit confused. The virsh documentation[0]
> says: “For compatibility purposes, --persistent behaves like --config
> for an offline domain, and like --live --config for a running domain. ”
> So wouldn’t it be right, that we *must not* touch the live config if
> the domain is offline, while we *should* indeed touch it when it’s
> online? Or is the documentation outdated here? I would really appreciate
> it if you could clarify.
Note that --persistent is not a concept exposed in the libvirt API,
it is a convenience invented for virsh only.
This is the logic for how --persistent works:
if (config || persistent)
flags |= VIR_DOMAIN_AFFECT_CONFIG;
if (live)
flags |= VIR_DOMAIN_AFFECT_LIVE;
if (persistent &&
virDomainIsActive(dom) == 1)
flags |= VIR_DOMAIN_AFFECT_LIVE;
IOW, when --persistent is given, the offline config will always be
updated. If the domain is running, then the live config will also
be updated.
With regards,
Daniel
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