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Date:   Fri, 21 Oct 2022 10:33:44 -0400
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Subject: Re: [Patch v8 12/12] RDMA/mana_ib: Add a driver for Microsoft Azure
 Network Adapter
To:     Long Li <longli@microsoft.com>,
        Bernard Metzler <BMT@zurich.ibm.com>,
        KY Srinivasan <kys@microsoft.com>,
        Haiyang Zhang <haiyangz@microsoft.com>,
        Stephen Hemminger <sthemmin@microsoft.com>,
        Wei Liu <wei.liu@kernel.org>, Dexuan Cui <decui@microsoft.com>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        Jason Gunthorpe <jgg@ziepe.ca>,
        Leon Romanovsky <leon@kernel.org>,
        "edumazet@google.com" <edumazet@google.com>,
        "shiraz.saleem@intel.com" <shiraz.saleem@intel.com>,
        Ajay Sharma <sharmaajay@microsoft.com>
Cc:     "linux-hyperv@vger.kernel.org" <linux-hyperv@vger.kernel.org>,
        "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-rdma@vger.kernel.org" <linux-rdma@vger.kernel.org>
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From:   Tom Talpey <tom@talpey.com>
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On 10/20/2022 4:42 PM, Long Li wrote:
>> [Bernard wrote...]

>>> +	props->max_qp_wr = MAX_SEND_BUFFERS_PER_QUEUE;
>>> +
>>> +	/*
>>> +	 * max_cqe could be potentially much bigger.
>>> +	 * As this version of driver only support RAW QP, set it to the same
>>> +	 * value as max_qp_wr
>>> +	 */
>>> +	props->max_cqe = MAX_SEND_BUFFERS_PER_QUEUE;
>>> +
>>> +	props->max_mr_size = MANA_IB_MAX_MR_SIZE;
>>> +	props->max_mr = INT_MAX;
>>
>> How the 24 bit wide MR keys can handle INT_MAX unique
>> MR's?
> 
> Not sure if I understand this correctly, lkey and rkey are u32 in ib_mr.

The upper 8 bits of an ib_mr remote token are reserved for use as a
rotating key, this allows a consumer to more safely reuse an ib_mr
without having to overallocate large region pools.

Tom.