[libvirt] [PATCH 2/5] virsh: Fix semantics of --config for "update-device" command

[Peter Krempa]

On 03/27/13 16:22, Laine Stump wrote:
> On 03/21/2013 12:42 PM, Peter Krempa wrote:
>> The man page states that with --config the next boot is affected. This
>> can be understood as if _only_ the next bood was affected. This isn't
>> true if the machine is running.
>
> Are you certain of that? My understanding was that when --config was
> specified, *only* the persistent config should be changed, but not the
> live state, regardless of whether or not the domain is running.
> Otherwise, there is no way to change just the persistent config of a
> running domain.

Yes, that's why I'm doing this. Before this patch --config meant "modify 
the persistent config along with the live change" and there was no way 
to use this virsh command to change the next-boot config if the domain 
was running.

>
> Or is your explanation incorrect, and the code correct?
>
> Here is what I *thought* was the meaning of these options:
>
> --config - only change the persistent config, but not the
>             live state. The command should fail for a transient
>             domain.
>
> --live   - only change the live state, but not the persistent config.
>             The command should fail for a domain that isn't running.
>
> --current - useless (really, I mean that) because its meaning is different
>              depending on whether or not the domain is running

Yes those we understand in the same way.

>
> --persistent - deprecated synonym for --config

This used to be the synonym for config, but this might be undestood as 
the option you are missing later on ...

>
> no option - also useless because it means the same thing as --current
>
> What's missing: a way to say "change both live state and persistent
> config as appropriate"

Well, this patch would abuse the --persistent flag for this purpose. It 
adds _CONFIG always and _LIVE in case the domain is up.
>
> After discussing it on the list, in the name of consistency I actually
> very reluctantly implemented this same logic for virsh net-update even
> though I thought it was terrible. Did I get it wrong?

No, you've got it correct. Well, except for --persistent but I'm less 
sure about that than you.

>
> So what is the *real* meaning of each of these options? (and are you
> sure you're not changing the meaning of any of them?)

Except for --persistent, the meaning seems to be well defined now and 
used appropriately in new places. The problem is with the legacy API's 
that didn't take up on this approach yet.

>
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