linux-kernel - Re: [RFC 1/8] Introduce Peer-to-Peer memory (p2pmem) device

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Message-ID: <190d9a89-e227-e410-5886-ee2e20a9b941@deltatee.com>
Date:   Tue, 25 Apr 2017 10:58:40 -0600
From:   Logan Gunthorpe <logang@...tatee.com>
To:     Marta Rybczynska <mrybczyn@...ray.eu>
Cc:     Sinan Kaya <okaya@...eaurora.org>, Christoph Hellwig <hch@....de>,
        Sagi Grimberg <sagi@...mberg.me>,
        "James E.J. Bottomley" <jejb@...ux.vnet.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        Jens Axboe <axboe@...nel.dk>,
        Steve Wise <swise@...ngridcomputing.com>,
        Stephen Bates <sbates@...thlin.com>,
        Max Gurtovoy <maxg@...lanox.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Keith Busch <keith.busch@...el.com>,
        Jason Gunthorpe <jgunthorpe@...idianresearch.com>,
        linux-pci@...r.kernel.org, linux-scsi@...r.kernel.org,
        linux-nvme@...ts.infradead.org, linux-rdma@...r.kernel.org,
        linux-nvdimm@...ts.01.org, linux-kernel@...r.kernel.org,
        Alex Williamson <alex.williamson@...hat.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>
Subject: Re: [RFC 1/8] Introduce Peer-to-Peer memory (p2pmem) device



On 25/04/17 05:58 AM, Marta Rybczynska wrote:
> I would add one issue that doesn't seem to be addressed: in my experience
> P2P doesn't work when IOMMU activated. It works best with deactivation at
> the BIOS level, even the kernel options are not enough in some cases.

Well this would likely be addressed by 'arch_p2p_cross_segment' as
proposed by Jason.

Logan