Re: [PATCH 0/2] A General Accelerator Framework, WarpDrive

[Kenneth Lee <liguozhu@hisilicon.com>]

On Thu, Aug 15, 2019 at 01:04:24PM -0400, Jerome Glisse wrote:
> Date: Thu, 15 Aug 2019 13:04:24 -0400
> From: Jerome Glisse <jglisse@redhat.com>
> To: Zhangfei Gao <zhangfei.gao@linaro.org>
> CC: linux-accelerators@lists.ozlabs.org, Greg Kroah-Hartman
>  <gregkh@linuxfoundation.org>, linux-kernel@vger.kernel.org, Arnd Bergmann
>  <arnd@arndb.de>
> Subject: Re: [PATCH 0/2] A General Accelerator Framework, WarpDrive
> User-Agent: Mutt/1.11.3 (2019-02-01)
> Message-ID: <20190815170424.GA30916@redhat.com>
> 
> On Wed, Aug 14, 2019 at 05:34:23PM +0800, Zhangfei Gao wrote:
> > *WarpDrive* is a general accelerator framework for the user application to
> > access the hardware without going through the kernel in data path.
> > 
> > WarpDrive is the name for the whole framework. The component in kernel
> > is called uacce, meaning "Unified/User-space-access-intended Accelerator
> > Framework". It makes use of the capability of IOMMU to maintain a
> > unified virtual address space between the hardware and the process.
> > 
> > WarpDrive is intended to be used with Jean Philippe Brucker's SVA
> > patchset[1], which enables IO side page fault and PASID support. 
> > We have keep verifying with Jean's sva/current [2]
> > We also keep verifying with Eric's SMMUv3 Nested Stage patch [3]
> > 
> > This series and related zip & qm driver as well as dummy driver for qemu test:
> > https://github.com/Linaro/linux-kernel-warpdrive/tree/5.3-rc1-warpdrive-v1
> > zip driver already been upstreamed.
> > zip supporting uacce will be the next step.
> > 
> > The library and user application:
> > https://github.com/Linaro/warpdrive/tree/wdprd-v1-current
> 
> Do we want a new framework ? I think that is the first question that
> should be answer here. Accelerator are in many forms and so far they
> never have been enough commonality to create a framework, even GPUs
> with the drm is an example of that, drm only offer share framework
> for the modesetting part of the GPU (as thankfully monitor connector
> are not specific to GPU brands :))
> 
> FPGA is another example the only common code expose to userspace is
> about bitstream management AFAIK.
> 
> I would argue that a framework should only be created once there is
> enough devices with same userspace API. Meanwhile you can provide
> in kernel helper that allow driver to expose same API. If after a
> while we have enough device driver which all use that same in kernel
> helpers API then it will a good time to introduce a new framework.
> Meanwhile this will allow individual device driver to tinker with
> their API and maybe get to something useful to more devices in the
> end.
> 
> Note that what i propose also allow userspace code sharing for all
> driver that use the same in kernel helper.
> 
> Cheers,
> Jérôme

Hi, Jerome, I explain the idea here: https://zhuanlan.zhihu.com/p/79680889. We
think this is a comment requirement for eveybody. Hope this can help the
discussion. Thanks

-- 
			-Kenneth(Hisilicon)