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From: Jason Gunthorpe <jgunthorpe-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
To: Stephen Warren <swarren-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
Cc: Yishai Hadas <yishaih-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>,
	linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: ConnectX-3 on non-coherent AARCH64 system
Date: Fri, 10 Mar 2017 10:06:26 -0700	[thread overview]
Message-ID: <20170310170626.GE22960@obsidianresearch.com> (raw)
In-Reply-To: <b01684b6-ba4a-65cc-ea20-b578e1e2fa2e-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>

On Thu, Mar 09, 2017 at 04:59:40PM -0700, Stephen Warren wrote:

> However, when I run the same test on a (non-cache-coherent) AArch64 (ARMv8)
> machine (Cortex-A57, NVIDIA Tegra), the application does not work. In
> particular, ivc_poll_cq() returns -2 when the application waits for an
> ibv_post_send/recv() to complete.

User space verbs are not supported on non-cache-coherent architectures
for kernel bypass adapters and probably never will be.

Ideally the kernel would not create the uverbs device for DMA drivers
on such architectures.. Is there a kernel API to detect cache
incoherence?

> than e.g. the kernel filling in the CQ), and there don't appear to be any
> cache invalidation operations anywhere in libmlx4 (I'm not even sure if
> cache manipulation is possible from user-space on ARM). I also
> couldn't find

Precisely.

Jason
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  parent reply	other threads:[~2017-03-10 17:06 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-03-09 23:59 ConnectX-3 on non-coherent AARCH64 system Stephen Warren
     [not found] ` <b01684b6-ba4a-65cc-ea20-b578e1e2fa2e-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
2017-03-10 17:06   ` Jason Gunthorpe [this message]
     [not found]     ` <20170310170626.GE22960-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
2017-03-13 16:43       ` Stephen Warren
     [not found]         ` <40698e27-8b17-df09-8165-40420f16a37e-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>
2017-03-13 16:55           ` Jason Gunthorpe
2017-03-13 17:38           ` Christoph Lameter

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