linux-kernel - Re: [RFC PATCH 3/3] mm/map_contig: Add mmap(MAP

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Message-ID: <267dbccf-5649-7a7c-b85d-66546c0913cc@mellanox.com>
Date:   Mon, 16 Oct 2017 14:09:03 +0300
From:   Guy Shattah <sguy@...lanox.com>
To:     Michal Nazarewicz <mina86@...a86.com>,
        Michal Hocko <mhocko@...nel.org>,
        Christopher Lameter <cl@...ux.com>
Cc:     Mike Kravetz <mike.kravetz@...cle.com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, linux-api@...r.kernel.org,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        "Aneesh Kumar K . V" <aneesh.kumar@...ux.vnet.ibm.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Anshuman Khandual <khandual@...ux.vnet.ibm.com>,
        Laura Abbott <labbott@...hat.com>,
        Vlastimil Babka <vbabka@...e.cz>
Subject: Re: [RFC PATCH 3/3] mm/map_contig: Add mmap(MAP_CONTIG) support



On 16/10/2017 13:33, Michal Nazarewicz wrote:
> On Sun, Oct 15 2017, Guy Shattah wrote:
>> Why have several driver specific implementation if you can generalize
>> the idea and implement an already existing POSIX standard?
> Why is there a need for contiguous allocation?

This was explained in detail during a talk delivered by me and 
Christopher Lameter
during Plumbers conference 2017 @ 
https://linuxplumbersconf.org/2017/ocw/proposals/4669
Please see the slides there.

> If generalisation is the issue, then the solution is to define a common
> API where user-space can allocate memory *in the context of* a device.
> This provides a ‘give me memory I can use for this device’ request which
> is what user space really wants.
Do you suggest to add a whole new common API instead of merely adding a 
flag to existing one?