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Subject: Re: [Xen-devel] [PATCH net-next] xen-netback: get rid of old udev
 related code
To:     David Miller <davem@davemloft.net>, pdurrant@amazon.com
Cc:     xen-devel@lists.xenproject.org, wei.liu@kernel.org,
        linux-kernel@vger.kernel.org, netdev@vger.kernel.org
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 <20191212.110513.1770889236741616001.davem@davemloft.net>
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Date:   Fri, 13 Dec 2019 06:40:38 +0100
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On 12.12.19 20:05, David Miller wrote:
> From: Paul Durrant <pdurrant@amazon.com>
> Date: Thu, 12 Dec 2019 13:54:06 +0000
> 
>> In the past it used to be the case that the Xen toolstack relied upon
>> udev to execute backend hotplug scripts. However this has not been the
>> case for many releases now and removal of the associated code in
>> xen-netback shortens the source by more than 100 lines, and removes much
>> complexity in the interaction with the xenstore backend state.
>>
>> NOTE: xen-netback is the only xenbus driver to have a functional uevent()
>>        method. The only other driver to have a method at all is
>>        pvcalls-back, and currently pvcalls_back_uevent() simply returns 0.
>>        Hence this patch also facilitates further cleanup.
>>
>> Signed-off-by: Paul Durrant <pdurrant@amazon.com>
> 
> If userspace ever used this stuff, I seriously doubt you can remove this
> even if it hasn't been used in 5+ years.

Hmm, depends.

This has been used by Xen tools in dom0 only. If the last usage has been
in a Xen version which is no longer able to run with current Linux in
dom0 it could be removed. But I guess this would have to be a rather old
version of Xen (like 3.x?).

Paul, can you give a hint since which Xen version the toolstack no
longer relies on udev to start the hotplug scripts?


Juergen