From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sagi Grimberg Subject: Re: [PATCH RFC v2 02/10] IB/core: Introduce Signature Verbs API Date: Sun, 3 Nov 2013 18:30:50 +0200 Message-ID: <52767A3A.50802@mellanox.com> References: <1383222255-22699-1-git-send-email-sagig@mellanox.com> <1383222255-22699-3-git-send-email-sagig@mellanox.com> <5273F6F4.3000300@acm.org> <52763E68.2040605@mellanox.com> <5276608D.2020605@acm.org> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <5276608D.2020605-HInyCGIudOg@public.gmane.org> Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Bart Van Assche , linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Cc: oren-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org, tzahio-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org List-Id: linux-rdma@vger.kernel.org On 11/3/2013 4:41 PM, Bart Van Assche wrote: > On 3/11/2013 4:15, Sagi Grimberg wrote: >> On 11/1/2013 8:46 PM, Bart Van Assche wrote: >>> On 31/10/2013 5:24, Sagi Grimberg wrote: >>>> +/** >>>> + * Signature T10-DIF block-guard types >>>> + */ >>>> +enum ib_t10_dif_bg_type { >>>> + IB_T10DIF_CRC, >>>> + IB_T10DIF_CSUM >>>> +}; >>> >>> In SPC-4 paragraph 4.22.4 I found that the T10-PI guard is the CRC >>> computed from the generator polynomial x^16 + x^15 + x^11 + x^9 + x^8 >>> + x^7 + x^5 + x^4 + x^2 + x + 1. Could you tell me where I can find >>> which guard computation method IB_T10DIF_CSUM corresponds to ? >>> >>> Bart. >> >> The IB_T10DIF_CSUM computation method corresponds to IP checksum rules. >> this is aligned with SHOST_DIX_GUARD_IP guard type. > > Since the declarations added in constitute an > interface definition I think it would help if it would be made more > clear what these two symbols stand for. How about mentioning the names > of the standards these two guard computation methods come from ? An > alternative is to add a comment like the one above > scsi_host_guard_type in which explains the two > guard computation methods well: > > /* > * All DIX-capable initiators must support the T10-mandated CRC > * checksum. Controllers can optionally implement the IP checksum > * scheme which has much lower impact on system performance. Note > * that the main rationale for the checksum is to match integrity > * metadata with data. Detecting bit errors are a job for ECC memory > * and buses. > */ > > Bart. > Agreed, I'll comment on each type correspondence (T10-DIF CRC checksum and IP checksum). Sagi. -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html