Re: [PATCH qemu-server v3] fix #5578: smbios: set serial number

[Manuel Federanko <m.federanko@proxmox.com>]

On 2026-04-07 3:26 PM, Dominik Csapak wrote:
> not sure if it was discussed off-list, but you didn't really
> address fionas comment about just adding this conditionally,
> e.g. via ostype or machine version
> 
> this will increase the config size by a bit and i guess
> most guest operating systems don't gain much from this?
> 
> i'm guilty of adding such flags unconditionally myself in the past
> (see vmgenid) but i think we should avoid that when possible
> 
> e.g. an empty config (qm create ID)
> looks like this currently:
> 
> ```
> boot:
> meta: creation-qemu=10.2.1,ctime=1775568119
> smbios1: uuid=a0f6c957-1c8b-439f-b25a-1e45dc151263
> vmgenid: 0ed5ca0d-0e72-4c1a-b62f-ad2f7aaa8819
> ```
> 
> with your patch it looks like this:
> 
> ```
> boot:
> meta: creation-qemu=10.2.1,ctime=1775568283
> smbios1: 
> base64=1,serial=UFZFLWM5OTY3ZDQwLTVlZTUtNDQ1My1hZDI0LTljZWUzODJmZTg1ZA==,uuid=c9967d40-5ee5-4453-ad24-9cee382fe85d
> vmgenid: 1c7fe857-3520-4a20-8e09-611a7fb1be3b
> ```
> 
> which is quite a bit of noise.

Agreed, I'm against magically setting this if we detect a specific OS,
since in theory any program on any OS can depend on the serial. Some
specific Microsoft software is the reason for this patch, but I would
be surprised if it is the only one.

> 
> If you think it's worthwhile to have a serial number for every guest,
> we could e.g. still give it to qemus commandline if it's
> missing in the config (especially if it's the same as the
> normal uuid, but prefixed with PVE-)
> IMHO it makes no sense having the same uuid twice in the config.
> 
> if someone sets a serial manually, we should use that of course.

That's a good idea - could there be a use-case of wanting the serial
to not be set? If that is not the case then I'd prefer this approach.

> sorry if any of these were discussed already, i checked the m-l
> but didn't find any discussion regarding this.
>
I'm not sure anymore tbh. I talked about this with Stoiko off-list,
but it might've only concerned the format/prefix of the serial.

Anyways thanks for the feedback.