> -----Original Message-----
> From: Jason Gunthorpe <jgg@xxxxxxxx>
> Sent: Monday, November 23, 2020 10:05 AM
> To: Xiong, Jianxin <jianxin.xiong@xxxxxxxxx>
> Cc: linux-rdma@xxxxxxxxxxxxxxx; dri-devel@xxxxxxxxxxxxxxxxxxxxx; Doug Ledford <dledford@xxxxxxxxxx>; Leon Romanovsky
> <leon@xxxxxxxxxx>; Sumit Semwal <sumit.semwal@xxxxxxxxxx>; Christian Koenig <christian.koenig@xxxxxxx>; Vetter, Daniel
> <daniel.vetter@xxxxxxxxx>
> Subject: Re: [PATCH rdma-core 3/5] pyverbs: Add dma-buf based MR support
>
> On Mon, Nov 23, 2020 at 09:53:02AM -0800, Jianxin Xiong wrote:
>
> > +cdef class DmaBuf:
> > + def __init__(self, size, unit=0):
> > + """
> > + Allocate DmaBuf object from a GPU device. This is done through the
> > + DRI device interface (/dev/dri/card*). Usually this requires the
> > + effective user id being root or being a member of the 'video' group.
> > + :param size: The size (in number of bytes) of the buffer.
> > + :param unit: The unit number of the GPU to allocate the buffer from.
> > + :return: The newly created DmaBuf object on success.
> > + """
> > + self.dmabuf_mrs = weakref.WeakSet()
> > + self.dri_fd = open('/dev/dri/card'+str(unit), O_RDWR)
> > +
> > + args = bytearray(32)
> > + pack_into('=iiiiiiq', args, 0, 1, size, 8, 0, 0, 0, 0)
> > + ioctl(self.dri_fd, DRM_IOCTL_MODE_CREATE_DUMB, args)
> > + a, b, c, d, self.handle, e, self.size = unpack('=iiiiiiq',
> > + args)
> > +
> > + args = bytearray(12)
> > + pack_into('=iii', args, 0, self.handle, O_RDWR, 0)
> > + ioctl(self.dri_fd, DRM_IOCTL_PRIME_HANDLE_TO_FD, args)
> > + a, b, self.fd = unpack('=iii', args)
> > +
> > + args = bytearray(16)
> > + pack_into('=iiq', args, 0, self.handle, 0, 0)
> > + ioctl(self.dri_fd, DRM_IOCTL_MODE_MAP_DUMB, args);
> > + a, b, self.map_offset = unpack('=iiq', args);
>
> Wow, OK
>
> Is it worth using ctypes here instead? Can you at least add a comment before each pack specifying the 'struct XXX' this is following?
>
The ioctl call only accept a bytearray, not sure how to use ctypes here. I will add
comments with the actual layout of the parameter structure.
> Does this work with normal Intel GPUs, like in a Laptop? AMD too?
>
Yes, the interface is generic and works with most GPUs. Works with AMD, too.
> Christian, I would be very happy to hear from you that this entire work is good for AMD as well
>
> Edward should look through this, but I'm glad to see something like this
>
> Thanks,
> Jason
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