From: Alejandro Lucero <alejandro.lucero@netronome.com>
To: Stephen Hemminger <stephen@networkplumber.org>
Cc: Zhe Tao <zhe.tao@intel.com>, dev <dev@dpdk.org>
Subject: Re: [dpdk-dev] [PATCH v1] igu_uio: fix IOMMU domain issue
Date: Wed, 11 May 2016 08:35:58 +0100 [thread overview]
Message-ID: <CAD+H990mt+5QEN0S0YLfnqBphwjQG3g1kaOeDNZtO+O8GXCOkw@mail.gmail.com> (raw)
In-Reply-To: <20160510085915.529b4af5@xeon-e3>
On Tue, May 10, 2016 at 4:59 PM, Stephen Hemminger <
stephen@networkplumber.org> wrote:
> On Tue, 10 May 2016 19:21:41 +0800
> Zhe Tao <zhe.tao@intel.com> wrote:
>
> > Problem:
> > The following operations will cause the igb_uio based DPDK
> > operation failed.
> > --Any device assignment through the kvm_assign_device interface,
> > this can be the pci-assign method in QEMU
> > --VFIO group attachment operation(attach to the container)
> > this can happens in vfio-pci assignment in QEMU
>
>
> If you have an IOMMU why not use VFIO instead, it is better.
>
It is not about VFIO against UIO but about how iommu domains are created
and destroyed by the (old) kernel when iommu=pt. So even with VFIO you can
have problems.
We have had problems like this and other due to our device (NFP) just
mapping up to 40 bits of address space. Old kernels used in LTS
distributions like Ubuntu are iommu buggy and you need to do things like
this mapping inside the driver for solving problems. By the way, using
SRIOV just adds more problems. It is not safe to use iommu=pt with 3.13.x
Ubuntu kernels.
It would be a good thing for the original patch to identify those kernels
where the problem was detected. Of course, there could be more kernels with
the same problem but that is more work to do.
next prev parent reply other threads:[~2016-05-11 7:35 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-10 11:21 Zhe Tao
2016-05-10 15:59 ` Stephen Hemminger
2016-05-11 7:35 ` Alejandro Lucero [this message]
2016-05-11 17:24 ` Ferruh Yigit
2016-07-08 17:27 ` Thomas Monjalon
2016-07-09 7:09 ` Ferruh Yigit
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