Re: [PATCH] xenstore-paths: Allow subnet prefix in IP address

Jürgen Groß <[email protected]> Wed, 22 Jul 2026 10:49:09 +0200

Newsgroups	org.xenproject.lists.xen-devel
Message-ID	<[email protected]>

On 22.07.26 09:14, Jan Beulich wrote:
> On 08.06.2026 11:49, Tu Dinh wrote:
>> In the guest-reported IP address in xenstore, it's useful to know which
>> subnet it belongs to.
>>
>> Add a specification for the IPv6 host address/prefix format specified by
>> RFC 4291.
>>
>> For the IPv4 address/prefix notation, as there seems to be no equivalent
>> RFC specifying the host address/prefix format, specify it ourselves.
>>
>> Signed-off-by: Tu Dinh <[email protected]>
> 
> Btw, even if get_maintainer.pl doesn't say so, it would help to Cc the
> maintainer of the component the doc for which is being modified.

Indeed.

I'm sharing Teddy's concerns. We just don't know who are potential consumers
of those Xenstore nodes. I know of at least three large SUSE customers using
Xen having written tooling accessing Xenstore.

What about adding another node for the prefix, like

   ~/attr/vif/$DEVID/ipv4/$INDEX/prefix = INTEGER


Juergen

> 
> Jan
> 
>> --- a/docs/misc/xenstore-paths.pandoc
>> +++ b/docs/misc/xenstore-paths.pandoc
>> @@ -78,12 +78,12 @@ VALUES are strings and can take the following forms:
>>   
>>   * MAC_ADDRESS -- 6 integers, in hexadecimal form, separated by ':',
>>                    specifying an IEEE 802.3 ethernet MAC address.
>> -* IPV4_ADDRESS -- 4 integers, in decimal form, separated by '.',
>> -                  specifying an IP version 4 address as described
>> -                  IETF RFC 791.
>> -* IPV6_ADDRESS -- Up to 8 integers, in hexadecimal form, separated
>> -                  by ':', specifying an IP version 6 address as
>> -                  described in IETF RFC 4291.
>> +* IPV4_ADDRESS -- An IP version 4 address as specified by IETF RFC 791,
>> +                  optionally appended with a "/prefix" value representing the
>> +                  prefix length of the host address's subnet, with "prefix"
>> +                  being a decimal integer in the range of 0 to 32.
>> +* IPV6_ADDRESS -- An IP version 6 address or abbreviated "address/prefix"
>> +                  combination as specified by IETF RFC 4291 and RFC 5952.
>>   
>>   Additional TAGS may follow as a comma separated set of the following
>>   tags enclosed in square brackets.
>

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