Re: kern/57409: Feature request: Make GPT detection on VND configuration optional (and/or disable it if configuration is originated from xbdback)

[Matthias Petermann <mp%petermann-it.de@localhost>]

The following reply was made to PR kern/57409; it has been noted by GNATS.

From: Matthias Petermann <mp%petermann-it.de@localhost>
To: gnats-bugs%netbsd.org@localhost, kern-bug-people%netbsd.org@localhost,
 gnats-admin%netbsd.org@localhost, netbsd-bugs%netbsd.org@localhost
Cc: 
Subject: Re: kern/57409: Feature request: Make GPT detection on VND
 configuration optional (and/or disable it if configuration is originated from
 xbdback)
Date: Mon, 12 Jun 2023 10:28:00 +0200

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 Hello,
 
 On 16.05.23 07:10, Michael van Elst wrote:
 > The following reply was made to PR kern/57409; it has been noted by GNATS.
 > 
 > From: mlelstv%serpens.de@localhost (Michael van Elst)
 > To: gnats-bugs%netbsd.org@localhost
 > Cc:
 > Subject: Re: kern/57409: Feature request: Make GPT detection on VND configuration optional (and/or disable it if configuration is originated from xbdback)
 > Date: Tue, 16 May 2023 05:05:57 -0000 (UTC)
 > 
 >   mp%petermann-it.de@localhost writes:
 >   
 >   >This can lead to problems if:
 >   
 >   > - the GUID of the GPT is already known in the system
 >   > - the GUID of the GPT partition is known in the system
 >   
 >   >Functionally this does not lead to any limitation, it is rather the error message that confuses and the feeling that the host should not try to interfere with the file images unless it is explicitly desired.
 >   
 >   It will "interfere" the same, if any other kind of label is used, just less noisy.
 >   
 >   
 >   >For testing it should be sufficient to create a new image with dd, configure it as VND, create a GPT with a partition on it and format it with FFS. Then unconfigure, copy the image to a second file and now copy both images one after the other with vndconfig. When configuring the second image, the error message should appear.
 >   
 >   When you clone a GPT based image, you should use 'gpt uuid -a' to create unique UUIDs on
 >   the copy to avoid such conflicts.
 >   
 
 Thanks for the tip with gpt uuid -a and the objective assessment. In the 
 end, I came to the conclusion that I might want a complex solution here 
 for a very specific problem for which there are quite a few better 
 solutions.
 
 For the backing store images of my VMs, I have now decided that I will 
 generally do without labels for the GPT partitions, in order to exclude 
 this as a source of collisions. I now rely exclusively on uuids, which I 
 either randomly assign during image creation, or - if the image is 
 created as a copy - are reassigned with gpt uuid -a as suggested by you.
 
 Consequently, this PR is no longer necessary and I would like to close it.
 
 Many thanks & best regards
 Matthias
 
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