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From: John Levon <levon@movementarian.org>
To: Keith Busch <kbusch@kernel.org>
Cc: linux-nvme@lists.infradead.org, hch@lst.de, sagi@grimberg.me
Subject: Re: [PATCH 2/3] nvme-pci: remove cached shadow doorbell offsets
Date: Mon, 4 Oct 2021 09:42:28 +0000	[thread overview]
Message-ID: <YVrMhJGFMHa2DUHs@li1368-133.members.linode.com> (raw)
In-Reply-To: <20200427235243.2268765-2-kbusch@kernel.org>

On Mon, Apr 27, 2020 at 04:52:42PM -0700, Keith Busch wrote:

> And when this feature is in use, the specification requires all queue
> updates use this mechanism, so don't don't treat the admin queue
> differently.

Also came across this patch of yours. We were wondering why Linux isn't spec
compliant for the admin queues. But this would cause implementation difficulties
for a controller, right? Currently we presume that the admin queue's shadow
doorbells aren't valid, so always look at BAR0 location. It's unclear what we'd
do if this change were made in Linux, presuming we need to support older Linux
versions. Some hack that observes a non-zero shadow value and presumes the
admin queue is using shadow doorbells?

Thoughts?

thanks
john

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  parent reply	other threads:[~2021-10-04  9:42 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-27 23:52 [PATCH 1/3] nvme-pci: clear shadow doorbell memory on resets Keith Busch
2020-04-27 23:52 ` [PATCH 2/3] nvme-pci: remove cached shadow doorbell offsets Keith Busch
2020-04-30  6:36   ` Dongli Zhang
2020-04-30 19:07     ` Keith Busch
2020-05-01 12:54   ` Christoph Hellwig
2021-10-04  9:42   ` John Levon [this message]
2020-04-27 23:52 ` [PATCH 3/3] nvme-pci: reshuffle nvme_queue members Keith Busch
2020-05-01 12:57   ` Christoph Hellwig
2020-05-01 15:08     ` Keith Busch
2020-05-01 15:12       ` Christoph Hellwig
2020-05-01 15:23         ` Keith Busch
2020-05-04 18:18       ` Keith Busch
2020-05-01 12:49 ` [PATCH 1/3] nvme-pci: clear shadow doorbell memory on resets Christoph Hellwig
2021-10-04  9:35 ` John Levon
2021-10-06 12:07   ` Keith Busch
2021-10-06 16:05     ` John Levon

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