From: Vitaly Kuznetsov <vkuznets@redhat.com>
To: Olaf Hering <olaf@aepfle.de>
Cc: kys@microsoft.com, gregkh@linuxfoundation.org,
        linux-kernel@vger.kernel.org, devel@linuxdriverproject.org
Subject: Re: move hyperv CHANNELMSG_UNLOAD from crashed kernel to kdump kernel
References: <20161207085110.GC1618@aepfle.de>
        <87r3594hef.fsf@vitty.brq.redhat.com>
        <20161215103402.GA6336@aepfle.de> <20161215103609.GB6336@aepfle.de>
Date: Thu, 15 Dec 2016 11:54:44 +0100
In-Reply-To: <20161215103609.GB6336@aepfle.de> (Olaf Hering's message of "Thu,
        15 Dec 2016 11:36:09 +0100")
Message-ID: <87inql4g3v.fsf@vitty.brq.redhat.com>
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Olaf Hering <olaf@aepfle.de> writes:

> On Thu, Dec 15, Olaf Hering wrote:
>
>> On Thu, Dec 15, Vitaly Kuznetsov wrote:
>> 
>> > I see a number of minor but at least one major issue against such move:
>> > At least for some Hyper-V versions (2012R2 for example)
>> > CHANNELMSG_UNLOAD_RESPONSE is delivered to the CPU which initially sent 
>> > CHANNELMSG_REQUESTOFFERS and on kdump we may not have this CPU up as
>> > we usually do kdump with nr_cpus=1 (and on the CPU which crashed). 
>> 
>> Since the kdump or kexec kernel will send the unload during boot I would
>> expect the response to arrive where it was sent, independent from the
>> number of cpus.
>
> Wait, I just noticed that "REQUESTOFFERS" now. That might be a reason
> why my suggestion will not work.
>

Yep, that's what I meant to say.

-- 
  Vitaly