linux-kernel - RE: [EXT] Re: [PATCH] nvme: Add abrupt shutdown support

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Date:   Tue, 6 Jul 2021 08:14:45 +0000
From:   "Shivamurthy Shastri (sshivamurthy)" <sshivamurthy@...ron.com>
To:     Keith Busch <kbusch@...nel.org>, Christoph Hellwig <hch@....de>
CC:     "axboe@...com" <axboe@...com>,
        "sagi@...mberg.me" <sagi@...mberg.me>,
        "linux-nvme@...ts.infradead.org" <linux-nvme@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "shiva.linuxworks@...il.com" <shiva.linuxworks@...il.com>
Subject: RE: [EXT] Re: [PATCH] nvme: Add abrupt shutdown support

Micron Confidential

Hi,

> 
> 
> On Mon, Jul 05, 2021 at 01:53:49PM +0200, Christoph Hellwig wrote:
> > On Mon, Jul 05, 2021 at 11:15:51AM +0000, Shivamurthy Shastri
> (sshivamurthy) wrote:
> > > For systems with passive electronic components to handle power-
> loss/battery-removal,
> > > CC.SHN=10b will help to achieve safer shutdown with relatively lower power
> back-up
> > > requirements (at lower cost).
> > >
> > > The module parameter gives flexibility to the host to decide shutdown type
> even during
> > > boot failure.
> >
> > If you have a device that always prefers an abrupt please introduce a TP
> > in the NVMe technical working group so that the hosts automatically
> > do the right thing.  Requiring sysadmin intervention using a global
> > kernel parameter is not the way to do this.

The abrupt shutdown notification is already part of NVMe Specification.

> 
> Is it the device that wants an abrupt shutdown or the platform? If the
> platform's power is running on limited back-up supply, and could inform
> the kernel's power management subsystem of this, then a driver could use
> that to determine if the quick shutdown is appropriate.

Yes, the platform is running on limited back-up supply. In this case, abrupt shutdown
option will help to achieve shutdown with relatively low back-up requirements.

Please let me know if you want to include the abrupt shutdown as part of 

static const struct dev_pm_ops nvme_dev_pm_ops = {
	.suspend	= nvme_suspend,
               .....


Thanks,
Shiva



Micron Confidential