From mboxrd@z Thu Jan  1 00:00:00 1970
From: Stephen Hemminger <stephen@networkplumber.org>
Subject: Re: [dpdk-stable] [PATCH v2] igb_uio: prevent reset for
 a list of devices
Date: Mon, 13 Nov 2017 15:46:56 -0800
Message-ID: <20171113154656.2e149727@xeon-e3>
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Cc: Ferruh Yigit <ferruh.yigit@intel.com>, Thomas Monjalon
 <thomas@monjalon.net>, dev@dpdk.org, Jianfeng Tan <jianfeng.tan@intel.com>,
 Jingjing Wu <jingjing.wu@intel.com>, Shijith Thotton
 <shijith.thotton@caviumnetworks.com>, Gregory Etelson <gregory@weka.io>,
 Harish Patil <harish.patil@cavium.com>, George Prekas
 <george.prekas@epfl.ch>, Sergio Gonzalez Monroy
 <sergio.gonzalez.monroy@intel.com>, Rasesh Mody <rasesh.mody@cavium.com>,
 Lee Roberts <lee.roberts@hpe.com>
To: Chas Williams <3chas3@gmail.com>
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On Wed, 8 Nov 2017 07:00:23 -0500
Chas Williams <3chas3@gmail.com> wrote:

> On Tue, Nov 7, 2017 at 5:26 PM, Ferruh Yigit <ferruh.yigit@intel.com> wro=
te:
> On 11/7/2017 12:47 PM, Chas Williams wrote:
> > I will confess I haven't looked into the issue too hard since I have a
> > workaround.=C2=A0 My first guess is that there is something going on wi=
th the IOMMU
> > and quiescing a PCI pass-through device/function from the guest (since =
I don't
> > think the IOMMU is "visible" to the guest) seems iffy.
> >
> > Most devices have some sort of reset to put the device into a known sta=
te for
> > setup/configuration (or enable/disable for the DMA engines).=C2=A0 If t=
his is done at
> > .dev_close(), shouldn't that be as sufficient as resetting the function?
>=20
> This is for the cases DPDK app terminated unexpectedly, proper exit path =
already
> does cleanup.
>=20
> Call a usermode helper from igb_uio that does an open/close on the device=
 about to be released?

usermode helper is hated by upstream kernel developers. There are many prob=
lems
such as what namespace and security.