Re: [PATCH] nvme: Enable acceleration feature of A64FX processor

From: Christoph Hellwig
Date: Tue Feb 05 2019 - 11:13:51 EST

On Tue, Feb 05, 2019 at 07:39:06AM -0700, Keith Busch wrote:
> > Standard PCIe devices can use Relaxed Ordering (RO) by setting Attr
> > field in the TLP header, however, this mechanism cannot be utilized if
> > the device does not support RO feature. Fujitsu A64FX processor has an
> > alternate feature to enable RO in its Root Port by setting the bit 56 of
> > DMA address. This mechanism enables to utilize RO feature even if the
> > device does not support standard PCIe RO.
> I think you're better of just purchasing devices that support the
> capability per spec rather than with a non-standard work around.

Agreed, this seems like a pretty gross hack.