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 01EEBC5ACD1 for ; Fri, 20 Feb 2026 16:20:15 +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-Transfer-Encoding:Content-Type:MIME-Version:References:Message-ID: Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=5Yh8YlZfWC+YQIPKrLCEYUXdbkvhoi+H4vPy+ESTo3I=; b=hlF/m91WJ5nbIZ5z7nuNN73wPX V/K3jFTyLwYjBAF1RioVZ4fywP6dH4xB1RK4J2MbE3cihhccEde3tEOHy2X0uRtv+LOnNAJ2AZRVP m49SAGCxlFNAwXygXXrfTwqy5Tfo8YOLrDZYouFZxLkHtEiBMhT4ZoCC5KLqLFT2v5vZiJnpqrRO0 KMmTyjv3agdIas6qXgQoQqwipe2HIzEKvB+QTsHKo924DHvol8EIkae+3NDPWZE1eDCct5DjOGjWY WZYkfuFnuEPHvUISrouk15WnJTdhlxb9ZL3y/KwQYxdlUZnWn42E5RZwyvys0kwzemWfkvj4qVLP1 Io/eH9fQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vtTEk-0000000FF3H-1cy6; Fri, 20 Feb 2026 16:20:14 +0000 Received: from verein.lst.de ([213.95.11.211]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1vtTEg-0000000FF1N-34R6 for linux-nvme@lists.infradead.org; Fri, 20 Feb 2026 16:20:13 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id 9F8A268B05; Fri, 20 Feb 2026 17:20:07 +0100 (CET) Date: Fri, 20 Feb 2026 17:20:07 +0100 From: Christoph Hellwig To: Caleb Sander Mateos Cc: Christoph Hellwig , Keith Busch , Jens Axboe , Sagi Grimberg , Chaitanya Kulkarni , linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/6] nvme: update nvme_id_ns OPTPERF constants Message-ID: <20260220162007.GA15462@lst.de> References: <20260220032809.758089-1-csander@purestorage.com> <20260220032809.758089-3-csander@purestorage.com> <20260220160741.GC15071@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: 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-20260220_082010_911191_5674DD44 X-CRM114-Status: GOOD ( 19.29 ) 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 Fri, Feb 20, 2026 at 08:17:29AM -0800, Caleb Sander Mateos wrote: > On Fri, Feb 20, 2026 at 8:07 AM Christoph Hellwig wrote: > > > > On Thu, Feb 19, 2026 at 08:28:05PM -0700, Caleb Sander Mateos wrote: > > > Since NVM Command Spec 1.1, OPTPERF comprises both bits 4 and 5 of > > > NSFEAT in the Identify Namespace structure. Replace NVME_NS_FEAT_IO_OPT, > > > which represented only bit 4, with NVME_NS_FEAT_OPTPERF_SHIFT and > > > NVME_NS_FEAT_OPTPERF_MASK. > > > > As you're deeper in this than me: do the older specs require the > > other bit to be cleared to zero and this is all compatible? Or do > > we need to guard it somehow? > > In NVM Command Set spec 1.0 (NVMe version 2.0), OPTPERF is only bit 4 > of NSFEAT and the higher bits are reserved. I think it seems > relatively safe to assume bit 5 will be reported as 0 on controllers > advertising older NVMe versions, but you're correct that the host > should technically check for version >= 2.1 before using bit 5. Let me > know which approach you'd prefer. Not entirely sure, but either way the code should have a big fat comment about this.