Re: [EXTERNAL] Re: [PATCH 05/12] net: mana: Set the DMA device max page size

Jason Gunthorpe
2022-05-18T16:05:35Z

On Wed, May 18, 2022 at 05:59:00AM +0000, Ajay Sharma wrote:
> Thanks Long.
> Hello Jason,
> I am the author of the patch.
> To your comment below :
> " As I've already said, you are supposed to set the value that limits to ib_sge and *NOT* the value that is related to ib_umem_find_best_pgsz. It is usually 2G because the ib_sge's typically work on a 32 bit length."
>
> The ib_sge is limited by the __sg_alloc_table_from_pages() which
> uses ib_dma_max_seg_size() which is what is set by the eth driver
> using dma_set_max_seg_size() . Currently our hw does not support
> PTEs larger than 2M.

*sigh* again it has nothing to do with *PTEs* in the HW.

Jason