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        "id": 83087,
        "web_url": "",
        "msgid": "<>",
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        "date": "2018-07-03T12:33:01",
        "subject": "Re: [dpdk-dev] [PATCH v2 0/6] use IOVAs check based on DMA mask",
        "submitter": {
            "id": 4,
            "url": "",
            "name": "Burakov, Anatoly",
            "email": ""
        "content": "On 03-Jul-18 1:09 PM, Alejandro Lucero wrote:\n> This patchset adds, mainly, a check for ensuring IOVAs are within a\n> restricted range due to addressing limitations with some devices. There\n> are two known cases: NFP and IOMMU VT-d emulation.\n> \n> With this check IOVAs out of range are detected and PMDs can abort\n> initialization. For the VT-d case, IOVA VA mode is allowed as long as\n> IOVAs are within the supported range, avoiding to forbid IOVA VA by\n> default.\n> \n> For the addressing limitations known cases, there are just 40(NFP) or\n> 39(VT-d) bits for handling IOVAs. When using IOVA PA, those limitations\n> imply 1TB(NFP) or 512M(VT-d) as upper limits, which is likely enough for\n> most systems. With machines using more memory, the added check will\n> ensure IOVAs within the range.\n> \n> With IOVA VA, and because the way the Linux kernel serves mmap calls\n> in 64 bits systems, 39 or 40 bits are not enough. It is possible to\n> give an address hint with a lower starting address than the default one\n> used by the kernel, and then ensuring the mmap uses that hint or hint plus\n> some offset. With 64 bits systems, the process virtual address space is\n> large enoguh for doing the hugepages mmaping within the supported range\n> when those addressing limitations exist. This patchset also adds a change\n> for using such a hint making the use of IOVA VA a more than likely\n> possibility when there are those addressing limitations.\n> \n> The check is not done by default but just when it is required. This\n> patchset adds the check for NFP initialization and for setting the IOVA\n> mode is an emulated VT-d is detected.\n> \n> This patchset applies on 17.11.3.\n> \n> Similar changes will be submitted to main DPDK branch soon.\n> \n> v2:\n>   - add get_addr_hint function\n>   - call munmap when hint given and not used by mmap\n>   - create dma mask in one step\n>   - refactor logs\n> \n> \n\nGeneral comment - new API's should probably be added to the .map files?",
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            "Subject": "Re: [dpdk-dev] [PATCH v2 0/6] use IOVAs check based on DMA mask",
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            "From": "\"Burakov, Anatoly\" <>",
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            "Date": "Tue, 3 Jul 2018 13:33:01 +0100",
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