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Fri, 30 Oct 2026 12:42:33 -0700 (PDT) Received: from medusa.lab.kspace.sh ([208.88.152.253]) by smtp.googlemail.com with ESMTPSA id 5a478bee46e88-36a429467cdsm9307441eec.19.2026.10.30.12.42.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 30 Oct 2026 12:42:31 -0700 (PDT) Date: Fri, 30 Oct 2026 12:42:29 -0700 From: Mohamed Khalfella To: Daniel Wagner Cc: Keith Busch , Jens Axboe , Christoph Hellwig , Sagi Grimberg , Justin Tee , Naresh Gottumukkala , Paul Ely , Hannes Reinecke , Chaitanya Kulkarni , James Smart , Randy Jennings , linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org, Hannes Reinecke Subject: Re: [PATCH v6 06/18] nvme: Rapid Path Failure Recovery read controller identify fields Message-ID: <20261030194229.GD122209-mkhalfella@purestorage.com> References: <20260920182936.2317916-1-mkhalfella@purestorage.com> <20260920182936.2317916-7-mkhalfella@purestorage.com> <179242896496.3619480.12975259904515722687.b4-review@b4> <20261019211849.GM2931-mkhalfella@purestorage.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261019211849.GM2931-mkhalfella@purestorage.com> On Mon 2026-10-19 14:18:53 -0700, Mohamed Khalfella wrote: > On Mon 2026-10-19 18:56:04 +0200, Daniel Wagner wrote: > > > TP8028 Rapid Path Failure added new fields to controller identify > > > response. Read CIU (Controller Instance Uniquifier), CIRN (Controller > > > Instance Random Number), and CCRL (Cross-Controller Reset Limit) from > > > controller identify response. Expose CIU and CIRN as sysfs attributes > > > so the values can be used directly by user if needed. > > > > What's the use case for it? This is an public/stable interface, > > it needs a justification and documentation > > CIU and CIRN identify an instance of an NVMe controller. For a given > CNTLID different values of CIU and CIRN identify different controller > instances of the same controller. The justification is that the values > allow the user to identify a specific controller instance. > > host# grep . /sys/class/nvme/nvme0/{cntlid,cirn,ciu} > /sys/class/nvme/nvme0/cntlid:1 > /sys/class/nvme/nvme0/cirn:42541d24813bb536 > /sys/class/nvme/nvme0/ciu:57 > host# nvme admin-passthru \ > --opcode 0x38 \ > --cdw10=$(( 0x1 | 0x57<<16 )) \ > --cdw12=$(( 0x42541d24813bb536 & 0xffffffff )) \ > --cdw13=$(( ( 0x42541d24813bb536 >> 32 ) & 0xffffffff )) \ > /dev/nvme1 > Admin Command Vendor Specific is Success and result: 0x00000000 > host# > > One usecase is to use the values to issue CCR command manually. Not that > I imagine one would want to do that, but if they want to do it they need > this information. CIU is also present in CCR log page. Someone reading > the log page might want to correlate a log page entry with a specific > controller, so they need the information to be exported somehow. > > diff --git a/Documentation/ABI/stable/sysfs-nvme b/Documentation/ABI/stable/sysfs-nvme > index a2f5d0710db4..ebc3634c1a96 100644 > --- a/Documentation/ABI/stable/sysfs-nvme > +++ b/Documentation/ABI/stable/sysfs-nvme > @@ -9,6 +9,17 @@ Description: > of the NVMe controller, as reported in the Identify > Controller data structure. > > +What: /sys/class/nvme/nvmeX/cirn > +What: /sys/class/nvme/nvmeX/ciu > +Date: October 2026 > +KernelVersion: 7.5 > +Contact: Mohamed Khalfella > +Description: > + Shows CIRN (Controller Instance Random Number) and CIU > + (Controller Instance Uniquifier) of the current instance > + of the NVMe controller as reported by Identify Controller > + data structure. > + > What: /sys/class/nvme/nvmeX/cntlid > Date: February 2016 > KernelVersion: 4.6 > > How about a diff like the one above for a documentation? I can add > something similar to the one above assuming the change will be merged in > 7.5. Or I can add it later on? Maybe in an -rc after the change is > merged? > > What do you think? Added the diff above to the patch. Let me know if you want me to modify it. > > > > > > Also add the nvme_fence_timeout_ms() helper that derives a fencing > > > timeout from the controller keep-alive timeout (kato). > > > > There is no user in this patch, introduce it when you use it. > > Moved the hunk to patch "nvme: Implement cross-controller reset recovery" > where the function is actually used. > > > > > -- > > Daniel Wagner