linux-kernel - Re: [PATCH 0/2] Drivers: hv: vmbus: make bus ids in sysfs persistent

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Message-ID: <87twer8y2w.fsf@vitty.brq.redhat.com>
Date:	Thu, 11 Aug 2016 11:16:39 +0200
From:	Vitaly Kuznetsov <vkuznets@...hat.com>
To:	KY Srinivasan <kys@...rosoft.com>
Cc:	"devel\@linuxdriverproject.org" <devel@...uxdriverproject.org>,
	"linux-kernel\@vger.kernel.org" <linux-kernel@...r.kernel.org>,
	"Haiyang Zhang" <haiyangz@...rosoft.com>
Subject: Re: [PATCH 0/2] Drivers: hv: vmbus: make bus ids in sysfs persistent

KY Srinivasan <kys@...rosoft.com> writes:

>> -----Original Message-----
>> From: Vitaly Kuznetsov [mailto:vkuznets@...hat.com]
>> Sent: Tuesday, August 9, 2016 1:46 AM
>> To: devel@...uxdriverproject.org
>> Cc: linux-kernel@...r.kernel.org; Haiyang Zhang <haiyangz@...rosoft.com>;
>> KY Srinivasan <kys@...rosoft.com>
>> Subject: [PATCH 0/2] Drivers: hv: vmbus: make bus ids in sysfs persistent
>> 
>> Bus ids for VMBus devices in /sys/bus/vmbus/devices/ are not guaranteed
>> to be persistent across reboot or kernel restart and this causes problems
>> for some tools. E.g. kexec tools use these ids to identify NIC on kdump.
>> Fix the issue by using relid from channel offer as the unique id instead
>> of an auto incremented counter.
>
> Relids are not persistent. It is only valid between a channel offer
> message and a relid released message (or an unload or initiate contact
> message, which invalidates all channels). This is an opaque number
> that the root generates and uses to track channels. There is no
> guarantee that the same type of channel (networking, storage, etc)
> will get the same relid on each reboot.
>

Thanks for the info,

can we use device_id (offermsg.offer.if_instance.b) instead?

-- 
  Vitaly