From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 477BDD16261 for ; Mon, 14 Oct 2024 13:25:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=pskFySbmN+qWegSafMykyZ0h8m12eCmqEI5KkcQFUuc=; b=HBC4vnC/q6OxkOJd989yMvc3Hw joD5+K0uwQOodHV9Uhznw1SyeAiy/P1TSVu60RZx8UgABiamBIFHZ/NI8ppyGff2+Qs0oCBWtVV+S pbvS6Ns2XHitPfjVADTZbQHgjz+z2guVC2MCglnIfqeg0uFidVqBawwvBCJkGX/e7uYAdMG04axv7 +oXu6ERDi38tiARDG4BzSPDYJ+6Wzcqax26HEaLnbfvirCOGdFe6PFraF867dIciiCI73hUI/pRLk 1j+cv1B9qD0UzJG8WIRe6elBk1h+/Nm1b2maSdcmcZCPQ+grpMXYjACEhCKu88Gjhnnslu6XwgxKr HI2CoKkA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1t0L54-00000005GMW-1FUd; Mon, 14 Oct 2024 13:25:50 +0000 Received: from verein.lst.de ([213.95.11.211]) by bombadil.infradead.org with esmtps (Exim 4.98 #2 (Red Hat Linux)) id 1t0JOw-00000004xWP-31WX for linux-nvme@lists.infradead.org; Mon, 14 Oct 2024 11:38:25 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id C13CD227AA8; Mon, 14 Oct 2024 13:38:09 +0200 (CEST) Date: Mon, 14 Oct 2024 13:38:09 +0200 From: Christoph Hellwig To: Damien Le Moal Cc: Christoph Hellwig , linux-nvme@lists.infradead.org, Keith Busch , Sagi Grimberg , Manivannan Sadhasivam , Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= , Kishon Vijay Abraham I , Bjorn Helgaas , Lorenzo Pieralisi , linux-pci@vger.kernel.org, Rick Wertenbroek , Niklas Cassel Subject: Re: [PATCH v2 4/5] PCI: endpoint: Add NVMe endpoint function driver Message-ID: <20241014113809.GA31551@lst.de> References: <20241011121951.90019-1-dlemoal@kernel.org> <20241011121951.90019-5-dlemoal@kernel.org> <20241014084424.GC23780@lst.de> <79e57ebb-eef7-48b1-b337-845d2ef6ff49@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <79e57ebb-eef7-48b1-b337-845d2ef6ff49@kernel.org> User-Agent: Mutt/1.5.17 (2007-11-01) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20241014_043814_929430_6A7A6CA8 X-CRM114-Status: GOOD ( 13.83 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On Mon, Oct 14, 2024 at 07:41:18PM +0900, Damien Le Moal wrote: > | | PCIe NVMe endpoint driver | | > | | (Handles BAR registers, | | > | | doorbells, IRQs, SQs, CQs | | > | | and DMA transfers) | | > | +---------------------------+ | > | | | > | +---------------------------+ | > | | NVMe fabrics host | | > | +---------------------------+ | That whole fabrics host here is broken. The PCI frontend needs to talk directly to the target code instead of doing a completely pointless roundtrip through the block layer. > Unless I am mistaken, if I use a PCI transport as the base for the endpoint > driver, I would be able to connect only to a PCIe nvme device as the backend, no > ? No. Any fabrisc transport (or frontend) can you any of the the backends (file / bdev and passthrough).