From mboxrd@z Thu Jan  1 00:00:00 1970
From: ebiederm@xmission.com (Eric W. Biederman)
Subject: Re: [patch iproute2 1/6] iproute2: ipa: show switch id
Date: Thu, 04 Dec 2014 10:15:04 -0600
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To: Jiri Pirko <jiri@resnulli.us>
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In-Reply-To: <1417683438-10935-2-git-send-email-jiri@resnulli.us> (Jiri
	Pirko's message of "Thu, 4 Dec 2014 09:57:13 +0100")
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Jiri Pirko <jiri@resnulli.us> writes:

Would someone please explain to me what a switch id is?

I looked in the kernel source, and I looked here and while I know
switches I don't have a clue what a switch id is.

My primary concern at this point is that you have introduced a global
identifier that is isn't a hardware property (it certainly does not look
like a mac address) and that is unique across network namespaces and
thus breaks checkpoint/restart (aka CRIU).

Also what in the world does PHYS mean in IFLA_PHYS_SWITCH_ID?  Does that
mean we can't have a purely software implementation of this interface?
Given that we will want a software implementation at some point
including PHYS in the name seems completely wrong.

> Signed-off-by: Jiri Pirko <jiri@resnulli.us>
> ---
>  include/linux/if_link.h | 1 +
>  ip/ipaddress.c          | 8 ++++++++
>  2 files changed, 9 insertions(+)
>
> diff --git a/include/linux/if_link.h b/include/linux/if_link.h
> index 4732063..a6e2594 100644
> --- a/include/linux/if_link.h
> +++ b/include/linux/if_link.h
> @@ -145,6 +145,7 @@ enum {
>  	IFLA_CARRIER,
>  	IFLA_PHYS_PORT_ID,
>  	IFLA_CARRIER_CHANGES,
> +	IFLA_PHYS_SWITCH_ID,
>  	__IFLA_MAX
>  };
>  
> diff --git a/ip/ipaddress.c b/ip/ipaddress.c
> index 4d99324..bd36a07 100644
> --- a/ip/ipaddress.c
> +++ b/ip/ipaddress.c
> @@ -589,6 +589,14 @@ int print_linkinfo(const struct sockaddr_nl *who,
>  				      b1, sizeof(b1)));
>  	}
>  
> +	if (tb[IFLA_PHYS_SWITCH_ID]) {
> +		SPRINT_BUF(b1);
> +		fprintf(fp, "switchid %s ",
> +			hexstring_n2a(RTA_DATA(tb[IFLA_PHYS_SWITCH_ID]),
> +				      RTA_PAYLOAD(tb[IFLA_PHYS_SWITCH_ID]),
> +				      b1, sizeof(b1)));
> +	}
> +
>  	if (tb[IFLA_OPERSTATE])
>  		print_operstate(fp, rta_getattr_u8(tb[IFLA_OPERSTATE]));