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From:   Vitaly Kuznetsov <vkuznets@redhat.com>
To:     Dexuan Cui <decui@microsoft.com>
Cc:     KY Srinivasan <kys@microsoft.com>,
        Haiyang Zhang <haiyangz@microsoft.com>,
        Stephen Hemminger <sthemmin@microsoft.com>,
        "sashal\@kernel.org" <sashal@kernel.org>,
        "linux-hyperv\@vger.kernel.org" <linux-hyperv@vger.kernel.org>,
        "linux-kernel\@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Michael Kelley <mikelley@microsoft.com>
Subject: Re: [PATCH 2/3] hv_utils: Support host-initiated hibernation request
In-Reply-To: <1568245130-70712-3-git-send-email-decui@microsoft.com>
References: <1568245130-70712-1-git-send-email-decui@microsoft.com> <1568245130-70712-3-git-send-email-decui@microsoft.com>
Date:   Thu, 12 Sep 2019 18:26:56 +0200
Message-ID: <87a7b9cwfj.fsf@vitty.brq.redhat.com>
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Dexuan Cui <decui@microsoft.com> writes:

> +static void perform_hibernation(struct work_struct *dummy)
> +{
> +	/*
> +	 * The user is expected to create the program, which can be a simple
> +	 * script containing two lines:
> +	 * #!/bin/bash
> +	 * echo disk > /sys/power/state

'systemctl hibernate' is what people do nowadays :-)

> +	 */
> +	static char hibernate_cmd[PATH_MAX] = "/sbin/hyperv-hibernate";
> +

Let's not do that (I remember when we were triggering network restart
from netvsc and it was a lot of pain).

Receiving hybernation request from the host is similar to pushing power
button on your desktop: an ACPI event is going to be generated and your
userspace will somehow react to it. I see two options:
1) We try to hook up some existing userspace (udev?)
2) We write a new hyperv-daemon handling the request (with a config file
instead of hardcoding please).

-- 
Vitaly