From: Klaus Jensen <its@irrelevant.dk>
To: Dmitry Fomichev <dmitry.fomichev@wdc.com>
Cc: "Fam Zheng" <fam@euphon.net>, "Kevin Wolf" <kwolf@redhat.com>,
"Damien Le Moal" <damien.lemoal@wdc.com>,
qemu-block@nongnu.org, "Niklas Cassel" <niklas.cassel@wdc.com>,
"Klaus Jensen" <k.jensen@samsung.com>,
qemu-devel@nongnu.org, "Maxim Levitsky" <mlevitsk@redhat.com>,
"Alistair Francis" <alistair.francis@wdc.com>,
"Keith Busch" <kbusch@kernel.org>,
"Philippe Mathieu-Daudé" <philmd@redhat.com>,
"Matias Bjorling" <matias.bjorling@wdc.com>
Subject: Re: [PATCH v7 04/11] hw/block/nvme: Support allocated CNS command variants
Date: Tue, 20 Oct 2020 10:21:18 +0200 [thread overview]
Message-ID: <20201020082118.GA178548@apples.localdomain> (raw)
In-Reply-To: <20201019021726.12048-5-dmitry.fomichev@wdc.com>
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On Oct 19 11:17, Dmitry Fomichev wrote:
(snip)
> CAP.CSS (together with the I/O Command Set data structure) defines
> what command sets are supported by the controller.
>
> CC.CSS (together with Set Profile) can be set to enable a subset of
> the available command sets.
>
> Even if a user configures CC.CSS to e.g. Admin only, NVM namespaces
> will still be attached (and thus marked as active).
> Similarly, if a user configures CC.CSS to e.g. NVM, ZNS namespaces
> will still be attached (and thus marked as active).
>
> However, any operation from a disabled command set will result in a
> Invalid Command Opcode.
>
This part of the commit message seems irrelevant to the patch.
> Add a new Boolean namespace property, "attached", to provide the most
> basic namespace attachment support. The default value for this new
> property is true. Also, implement the logic in the new CNS values to
> include/exclude namespaces based on this new property. The only thing
> missing is hooking up the actual Namespace Attachment command opcode,
> which will allow a user to toggle the "attached" flag per namespace.
>
Without Namespace Attachment support, the sole purpose of this parameter
is to allow unusable namespace IDs to be reported. I have no problems
with adding support for the additional CNS values. They will return
identical responses, but I think that is good enough for now.
When it is not really needed, we should be wary of adding a parameter
that is really hard to get rid of again.
> The reason for not hooking up this command completely is because the
> NVMe specification requires the namespace management command to be
> supported if the namespace attachment command is supported.
>
There are many ways to support Namespace Management, and there are a lot
of quirks with each of them. Do we use a big blockdev and carve out
namespaces? Then, what are the semantics of an image resize operation?
Do we dynamically create blockdev devices - thats sounds pretty nice,
but might have other quirks and the attachment is not really persistent.
I think at least the "attached" parameter should be x-prefixed, but
better, leave it out for now until we know how we want Namespace
Attachment and Management to be implemented.
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next prev parent reply other threads:[~2020-10-20 8:26 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-19 2:17 [PATCH v7 00/11] hw/block/nvme: Support Namespace Types and Zoned Namespace Command Set Dmitry Fomichev
2020-10-19 2:17 ` [PATCH v7 01/11] hw/block/nvme: Add Commands Supported and Effects log Dmitry Fomichev
2020-10-19 19:22 ` Keith Busch
2020-10-19 20:16 ` Klaus Jensen
2020-10-20 23:04 ` Dmitry Fomichev
2020-10-19 2:17 ` [PATCH v7 02/11] hw/block/nvme: Generate namespace UUIDs Dmitry Fomichev
2020-10-19 19:24 ` Keith Busch
2020-10-19 19:30 ` Klaus Jensen
2020-10-19 2:17 ` [PATCH v7 03/11] hw/block/nvme: Add support for Namespace Types Dmitry Fomichev
2020-10-19 19:51 ` Keith Busch
2020-10-19 20:53 ` Klaus Jensen
2020-10-21 1:50 ` Dmitry Fomichev
2020-10-19 2:17 ` [PATCH v7 04/11] hw/block/nvme: Support allocated CNS command variants Dmitry Fomichev
2020-10-19 20:07 ` Keith Busch
2020-10-20 8:21 ` Klaus Jensen [this message]
2020-10-20 23:09 ` Dmitry Fomichev
2020-10-19 2:17 ` [PATCH v7 05/11] hw/block/nvme: Support Zoned Namespace Command Set Dmitry Fomichev
2020-10-19 9:50 ` Klaus Jensen
2020-10-19 15:55 ` Klaus Jensen
2020-10-19 12:33 ` Klaus Jensen
2020-10-20 11:08 ` Klaus Jensen
2020-10-21 10:26 ` Klaus Jensen
2020-10-21 23:19 ` Dmitry Fomichev
2020-10-19 2:17 ` [PATCH v7 06/11] hw/block/nvme: Introduce max active and open zone limits Dmitry Fomichev
2020-10-19 2:17 ` [PATCH v7 07/11] hw/block/nvme: Support Zone Descriptor Extensions Dmitry Fomichev
2020-10-19 2:17 ` [PATCH v7 08/11] hw/block/nvme: Add injection of Offline/Read-Only zones Dmitry Fomichev
2020-10-19 11:42 ` Klaus Jensen
2020-10-20 23:01 ` Dmitry Fomichev
2020-10-19 2:17 ` [PATCH v7 09/11] hw/block/nvme: Document zoned parameters in usage text Dmitry Fomichev
2020-10-19 2:17 ` [PATCH v7 10/11] hw/block/nvme: Separate read and write handlers Dmitry Fomichev
2020-10-20 8:28 ` Klaus Jensen
2020-10-20 12:36 ` Keith Busch
2020-10-20 23:05 ` Dmitry Fomichev
2020-10-19 2:17 ` [PATCH v7 11/11] hw/block/nvme: Merge nvme_write_zeroes() with nvme_write() Dmitry Fomichev
2020-10-20 8:29 ` Klaus Jensen
2020-10-19 7:32 ` [PATCH v7 00/11] hw/block/nvme: Support Namespace Types and Zoned Namespace Command Set Niklas Cassel
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