Re: [PATCH rdma-core v7 4/6] pyverbs: Add dma-buf based MR support

From: Daniel Vetter <daniel@ffwll.ch>
To: "Xiong, Jianxin" <jianxin.xiong@intel.com>
Cc: Yishai Hadas <yishaih@nvidia.com>,
	Leon Romanovsky <leon@kernel.org>,
	linux-rdma <linux-rdma@vger.kernel.org>,
	Edward Srouji <edwards@nvidia.com>,
	Gal Pressman <galpress@amazon.com>,
	dri-devel <dri-devel@lists.freedesktop.org>,
	Jason Gunthorpe <jgg@ziepe.ca>,
	Doug Ledford <dledford@redhat.com>,
	"Vetter, Daniel" <daniel.vetter@intel.com>,
	Christian Koenig <christian.koenig@amd.com>
Subject: Re: [PATCH rdma-core v7 4/6] pyverbs: Add dma-buf based MR support
Date: Wed, 3 Feb 2021 18:53:19 +0100	[thread overview]
Message-ID: <CAKMK7uHAD5FbDPeT2cD03HjHhvmMMG__muXqo=rTjd=htSMhtg@mail.gmail.com> (raw)
In-Reply-To: <MW3PR11MB455563A3F337F789613A9940E5B49@MW3PR11MB4555.namprd11.prod.outlook.com>

On Wed, Feb 3, 2021 at 5:57 PM Xiong, Jianxin <jianxin.xiong@intel.com> wrote:
>
> > -----Original Message-----
> > From: Leon Romanovsky <leon@kernel.org>
> > Sent: Tuesday, February 02, 2021 10:03 PM
> > To: Daniel Vetter <daniel@ffwll.ch>
> > Cc: Xiong, Jianxin <jianxin.xiong@intel.com>; Jason Gunthorpe <jgg@ziepe.ca>; Gal Pressman <galpress@amazon.com>; Yishai Hadas
> > <yishaih@nvidia.com>; linux-rdma <linux-rdma@vger.kernel.org>; Edward Srouji <edwards@nvidia.com>; dri-devel <dri-
> > devel@lists.freedesktop.org>; Christian Koenig <christian.koenig@amd.com>; Doug Ledford <dledford@redhat.com>; Vetter, Daniel
> > <daniel.vetter@intel.com>
> > Subject: Re: [PATCH rdma-core v7 4/6] pyverbs: Add dma-buf based MR support
> >
>
> <...>
>
> > > > > > > > > +#include <drm/drm.h>
> > > > > > > > > +#include <drm/i915_drm.h> #include <drm/amdgpu_drm.h>
> > > > > > > > > +#include <drm/radeon_drm.h>
> > > > > > > >
> > > > > > > > I assume these should come from the kernel headers package, right?
> > > > > > >
> > > > > > > This is gross, all kernel headers should be placed in
> > > > > > > kernel-headers/* and "update" script needs to be extended to take drm/* files too :(.
> > > > > >
> > > > > > drm kernel headers are in the libdrm package. You need that
> > > > > > anyway for doing the ioctls (if you don't hand-roll the restarting yourself).
> > > > > >
> > > > > > Also our userspace has gone over to just outright copying the
> > > > > > driver headers. Not the generic headers, but for the rendering
> > > > > > side of gpus, which is the topic here, there's really not much generic stuff.
> > > > > >
> > > > > > > Jianxin, are you fixing it?
> > > > > >
> > > > > > So fix is either to depend upon libdrm for building, or have
> > > > > > copies of the headers included in the package for the
> > > > > > i915/amdgpu/radeon headers (drm/drm.h probably not so good idea).
> > > > >
> > > > > We should have a cmake test to not build the drm parts if it can't be built, and pyverbs should skip the tests.
> > > > >
> > > >
> > > > Yes, I will add a test for that. Also, on SLES, the headers could be under /usr/include/libdrm instead of /usr/include/drm. The make test
> > should check that and use proper path.
> > >
> > > Please use pkgconfig for this, libdrm installs a .pc file to make sure
> > > you can find the right headers.
> >
> > rdma-core uses cmake build system and in our case cmake find_library() is preferable over pkgconfig.
>
> Only the headers are needed, and they could be installed via either the libdrm-devel package or the kernel-headers package. The cmake find_path() command is more suitable here.

Except if your distro is buggy (or doesn't support any gpu drivers at
all) they will never be installed as part of kernel-headers.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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