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From: Jerome Glisse <jglisse@redhat.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Hellwig <hch@lst.de>,
	Dan Williams <dan.j.williams@intel.com>,
	Logan Gunthorpe <logang@deltatee.com>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 5/5] mm, hmm: mark hmm_devmem_{add, add_resource} EXPORT_SYMBOL_GPL
Date: Tue, 5 Jun 2018 14:24:38 -0400	[thread overview]
Message-ID: <20180605182438.GB4423@redhat.com> (raw)
In-Reply-To: <20180522143121.54d4ebced511277b923d31ba@linux-foundation.org>

On Tue, May 22, 2018 at 02:31:21PM -0700, Andrew Morton wrote:
> On Tue, 22 May 2018 08:32:36 +0200 Christoph Hellwig <hch@lst.de> wrote:
> 
> > On Mon, May 21, 2018 at 03:35:40PM -0700, Dan Williams wrote:
> > > The routines hmm_devmem_add(), and hmm_devmem_add_resource() are small
> > > wrappers around devm_memremap_pages(). The devm_memremap_pages()
> > > interface is a subset of the hmm functionality which has more and deeper
> > > ties into the kernel memory management implementation. It was an
> > > oversight that these symbols were not marked EXPORT_SYMBOL_GPL from the
> > > outset due to how they originally copied (and now reuse)
> > > devm_memremap_pages().
> > 
> > If we end up keeping this code: absolutely.  Then again I think without
> > an actual user this should have never been merged, and should be removed
> > until one shows up.
> > 
> 
> It wasn't simple.  Quite a lot of manufacturers were (are?) developing
> quite complex driver code which utilizes hmm.  Merging hmm to give a
> stable target for that development and in the expectation that those
> things would be coming along was a risk and I don't think we yet know
> the outcome.
> 
> Jerome, are you able to provide any updates on all of this?

Sorry for taking so long to reply to this, I am just back from vacation.

I posted a v1 for nouveau to use HMM back in April or early May. I want
to post a v2 soon in June. For it to get upstream it needs to fullfill
linux drm sub-system requirement which are an open source userspace for
any functionality added to GPU driver. Work for this have been going
on for a while too and userspace bits are slowly getting upstream inside
Mesa. I need to sync up to see what is still missing in Mesa.

So i won't be able to get nouveau HMM bits merge before the userspace
bits are merge too. I was hopping for 4.18 but more likely 4.19.

I know HMM have been a big chicken and egg thing and that timing for
the egg did not match the timing for the chicken :) But it is getting
there.


Also I expect more hardware and associated upstream driver to make use
of HMM but i can not comment further on that at this time because of
NDA.

Cheers,
Jérôme

  reply	other threads:[~2018-06-05 18:24 UTC|newest]

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-21 22:35 [PATCH 0/5] mm: rework hmm to use devm_memremap_pages Dan Williams
2018-05-21 22:35 ` [PATCH 1/5] mm, devm_memremap_pages: mark devm_memremap_pages() EXPORT_SYMBOL_GPL Dan Williams
2018-05-22  6:29   ` Christoph Hellwig
2018-05-21 22:35 ` [PATCH 2/5] mm, devm_memremap_pages: handle errors allocating final devres action Dan Williams
2018-05-21 23:10   ` Andrew Morton
2018-05-22  0:07     ` Dan Williams
2018-05-22 16:42       ` Logan Gunthorpe
2018-05-22 16:56         ` Dan Williams
2018-05-22 17:03           ` Logan Gunthorpe
2018-05-22 17:25             ` Dan Williams
2018-05-22 17:36               ` Logan Gunthorpe
2018-05-22  6:30   ` Christoph Hellwig
2018-05-21 22:35 ` [PATCH 3/5] mm, hmm: use devm semantics for hmm_devmem_{add, remove} Dan Williams
2018-05-22  6:30   ` Christoph Hellwig
2018-05-21 22:35 ` [PATCH 4/5] mm, hmm: replace hmm_devmem_pages_create() with devm_memremap_pages() Dan Williams
2018-05-22  6:31   ` Christoph Hellwig
2018-05-22 17:13   ` Logan Gunthorpe
2018-05-22 21:38     ` Dan Williams
2018-05-21 22:35 ` [PATCH 5/5] mm, hmm: mark hmm_devmem_{add, add_resource} EXPORT_SYMBOL_GPL Dan Williams
2018-05-22  6:32   ` Christoph Hellwig
2018-05-22 21:31     ` Andrew Morton
2018-06-05 18:24       ` Jerome Glisse [this message]
2018-05-24  0:10 ` [PATCH 0/5] mm: rework hmm to use devm_memremap_pages Jerome Glisse
2018-05-24  3:18   ` Dan Williams
2018-05-24  6:35     ` Christoph Hellwig
2018-05-29 22:22     ` Dave Airlie
2018-05-29 22:31       ` Dan Williams
2018-05-29 23:00         ` Dave Airlie
2018-05-29 23:33           ` Dan Williams
2018-06-05 18:48             ` Jerome Glisse
2018-06-05 22:19               ` Dave Airlie
2018-06-05 23:06                 ` Dan Williams
2018-06-06  0:08                   ` Jerome Glisse
2018-06-06  1:33                     ` Dan Williams
2018-06-06  7:14                       ` Christoph Hellwig
2018-06-07 14:16                       ` Jerome Glisse
2018-06-07 18:39                         ` Dan Williams

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