netdev - Re: [PATCH net 2/2] hsr: Follow standard for HSRv0 supervision frames

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Message-ID: <20251112115906.esS_ffL3@linutronix.de>
Date: Wed, 12 Nov 2025 12:59:06 +0100
From: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To: Felix Maurer <fmaurer@...hat.com>
Cc: netdev@...r.kernel.org, davem@...emloft.net, edumazet@...gle.com,
	kuba@...nel.org, pabeni@...hat.com, horms@...nel.org,
	liuhangbin@...il.com, m-karicheri2@...com, arvid.brodin@...en.se
Subject: Re: [PATCH net 2/2] hsr: Follow standard for HSRv0 supervision frames

On 2025-11-12 12:01:51 [+0100], Felix Maurer wrote:
> > You say HSRv0 while I don't see this mentioned at all. And you limit the
> > change to prot_version == 0. So maybe this was once and removed from the
> > standard.
> 
> My description for the path_id is from IEC 62439-3:2010. As far as I
> know, the HSRv0/HSRv1 terminology is only used in the kernel. AFAIK, our
> version 0/1 refers to the value in the SupVersion field of the HSR
> supervision frames. The SupVersion is defined as 0 in IEC 62439-3:2010
> and defined as 1 in IEC 62439-3:2012 and following.

This is what I assumed. I don't have any older specification, I have
here SupVersion always defined as 1.

> The definition for the SupVersion field also states: "Implementation of
> version X of the protocol shall interpret [...] version <=X frames
> exactly as specified for the version concerned." (in IEC
> 62439-3:{2010,2012,2016,2021})
> 
> I read from this that if we implement HSRv0 we should follow the latest
> specification for this version, i.e., the latest specification with
> SupVersion defined as 0 (which would be IEC 62439-3:2010). This is also
> why I limited the change to prot_version == 0 (maybe we should have some
> helpers like hsr_is_v{0,1}() to make these conditions a bit more self
> explanatory).

Based on the explanation, the limit to prot_version is the reasonable
thing to do.

> Thanks,
>    Felix

Sebastian