On Tue, Jul 28, 2020 at 06:26:08PM +0200, Greg KH wrote:

On Mon, Jul 27, 2020 at 03:44:33PM -0700, Jonathan Lemon wrote:

quoted

From: Jonathan Lemon <redacted>

Netgpu provides a data path for zero-copy sends and receives
without having the host CPU touch the data.  Protocol processing
is done on the host CPU, while data is DMA'd to and from DMA
mapped memory areas.  The initial code provides transfers between
(mlx5 / host memory) and (mlx5 / nvidia GPU memory).

The use case for this module are GPUs used for machine learning,
which are located near the NICs, and have a high bandwidth PCI
connection between the GPU/NIC.

Do we have such a GPU driver in the kernel today?  We can't add new
apis/interfaces for no in-kernel users, as you well know.

No, that's what I'm trying to create.  But Jens pointed out that the
main sticking point here seems to be Nvidia, so I'll look into seeing
whether there are some AMD or Intel GPUS I can use.

There's lots of crazyness in this patch, but this is just really odd:

quoted

+#if IS_MODULE(CONFIG_NETGPU)
+#define MAYBE_EXPORT_SYMBOL(s)
+#else
+#define MAYBE_EXPORT_SYMBOL(s)	EXPORT_SYMBOL(s)
+#endif

Why is that needed at all?  Why does no one else in the kernel need such
a thing?

Really, this is just development code, allowing the netgpu to be built
as a loadable module.  I'll rip it out.

And why EXPORT_SYMBOL() and not EXPORT_SYMBOL_GPL() (I have to ask).

Shorter typing, didn't think to add _GPL, I'll do that.
-- 
Jonathan