Subject: Re: [PATCH 10/11] vfio: selftests: Add mlx5 driver - data path and memcpy ops

From: Jason Gunthorpe <[email-masked]>
Date: Tue, 5 May 2026 12:49:20 -0300

On Mon, May 04, 2026 at 10:41:08PM +0000, David Matlack wrote:
> On 2026-04-30 09:08 PM, Jason Gunthorpe wrote:
> 
> > @@ -1368,6 +1716,11 @@ static void mlx5st_init(struct vfio_pci_device *device)
> >  	mlx5st_alloc_pd(dev);
> >  	mlx5st_create_mkey(dev);
> >  
> > +	mlx5st_setup_datapath(dev);
> > +
> > +	device->driver.max_memcpy_size = 1 << 20;
> > +	device->driver.max_memcpy_count = SQ_WQE_CNT - 1;
> 
> What are these limits a function of? e.g. Is the 1MB size a hardware
> limit? Can we change SQ_WQE_CNT in the future to increase max count?

I have to check, I don't think there is a small limit on RDMA WRITE,
and SQ_WQE_CNT is just a number it could be somewhat bigger.

This may be a hold over from an ealier version where it was trying to
make a PAS array, and the PAS array was capped. I removed that but
would have missed this.

Jason