From: Christoph Hellwig <hch@lst.de>
To: Damien Le Moal <dlemoal@kernel.org>
Cc: Mike Christie <michael.christie@oracle.com>,
chaitanyak@nvidia.com, kbusch@kernel.org, hch@lst.de,
sagi@grimberg.me, joao.m.martins@oracle.com,
linux-nvme@lists.infradead.org, kvm@vger.kernel.org,
kwankhede@nvidia.com, alex.williamson@redhat.com,
mlevitsk@redhat.com
Subject: Re: [PATCH RFC 03/11] nvmet: Add nvmet_fabrics_ops flag to indicate SGLs not supported
Date: Thu, 13 Mar 2025 10:13:49 +0100 [thread overview]
Message-ID: <20250313091349.GA18939@lst.de> (raw)
In-Reply-To: <970e0d79-f338-4803-92c4-255156a8257e@kernel.org>
On Thu, Mar 13, 2025 at 06:02:29PM +0900, Damien Le Moal wrote:
> On 3/13/25 14:18, Mike Christie wrote:
> > The nvmet_mdev_pci driver does not initially support SGLs. In some
> > prelim testing I don't think there will be a perf gain (the virt related
> > interface may be the major bottleneck so I may not notice) so I wasn't
> > sure if they will be required/needed. This adds a nvmet_fabrics_ops flag
> > so we can tell nvmet core to tell the host we do not supports SGLS.
>
> That is a major spec violation as NVMe fabrics mandates SGL support.
But this is a PCIe controller implementation, not fabrics.
Fabrics does not support PRPs and has very different SGLs from the
PCIe ones. The fact that the spec conflates those in very confusing
ways is one of the big mistakes in the spec.
next prev parent reply other threads:[~2025-03-13 9:13 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-03-13 5:18 [PATCH RFC 00/11] nvmet: Add NVMe target mdev/vfio driver Mike Christie
2025-03-13 5:18 ` [PATCH RFC 01/11] nvmet: Remove duplicate uuid_copy Mike Christie
2025-03-13 6:36 ` Christoph Hellwig
2025-03-13 8:59 ` Damien Le Moal
2025-03-13 17:20 ` Keith Busch
2025-03-13 5:18 ` [PATCH RFC 02/11] nvmet: Export nvmet_add_async_event and add definitions Mike Christie
2025-03-13 6:36 ` Christoph Hellwig
2025-03-13 17:50 ` Mike Christie
2025-03-13 5:18 ` [PATCH RFC 03/11] nvmet: Add nvmet_fabrics_ops flag to indicate SGLs not supported Mike Christie
2025-03-13 6:37 ` Christoph Hellwig
2025-03-13 9:02 ` Damien Le Moal
2025-03-13 9:13 ` Christoph Hellwig [this message]
2025-03-13 9:16 ` Damien Le Moal
2025-03-13 17:19 ` Mike Christie
2025-03-13 5:18 ` [PATCH RFC 04/11] nvmet: Add function to get nvmet_fabrics_ops from trtype Mike Christie
2025-03-13 9:03 ` Damien Le Moal
2025-03-13 5:18 ` [PATCH RFC 05/11] nvmet: Add function to print trtype Mike Christie
2025-03-13 5:18 ` [PATCH RFC 06/11] nvmet: Allow nvmet_alloc_ctrl users to specify the cntlid Mike Christie
2025-03-13 5:18 ` [PATCH RFC 07/11] nvmet: Add static controller support to configfs Mike Christie
2025-03-13 5:18 ` [PATCH RFC 08/11] nvmet: Add shadow doorbell support Mike Christie
2025-03-13 5:18 ` [PATCH RFC 09/11] nvmet: Add helpers to find and get static controllers Mike Christie
2025-03-13 5:18 ` [PATCH RFC 10/11] nvmet: Add addr fam and trtype for mdev pci driver Mike Christie
2025-03-13 6:42 ` Christoph Hellwig
2025-03-13 17:56 ` Mike Christie
2025-03-13 5:18 ` [PATCH RFC 11/11] nvmet: Add nvmet-mdev-pci driver Mike Christie
2025-03-13 5:32 ` [PATCH RFC 00/11] nvmet: Add NVMe target mdev/vfio driver Damien Le Moal
2025-03-13 6:47 ` Christoph Hellwig
2025-03-13 17:17 ` Mike Christie
2025-03-14 8:31 ` Hannes Reinecke
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