From: Stephen Hemminger <stephen@networkplumber.org>
To: amit sehas <cun23@yahoo.com>, maxime.coquelin@redhat.com
Cc: users@dpdk.org
Subject: Re: [dpdk-users] rte_virtio_pmd_init(): IOPL call failed - cannot use virtio PMD
Date: Fri, 3 Aug 2018 14:24:20 -0700 [thread overview]
Message-ID: <20180803142420.1198b64b@xeon-e3> (raw)
In-Reply-To: <1685797689.496737.1533140869394@mail.yahoo.com>
On Wed, 1 Aug 2018 16:27:49 +0000 (UTC)
amit sehas <cun23@yahoo.com> wrote:
> I am trying to run a dpdk application in docker and i get the above error ... the docker instance was run as below:
>
> docker run -dit --name <name> -v /hostlibpath:/contlibpath:ro fedora:26 bash
>
> i am new to dpdk, as a result i am quite lost as to where to look ...
>
> thanks
Short answer virtio requires DPDK process to be run as root.
In order for the virtio device to signal the underlying host it may need the in/out instructions.
These CPU instructions are normally privileged (only allowed in kernel) but on Linux there is
is a system call to allow a process with root (really CAP_SYS_RAWIO) to do these from userspace.
See iopl manual page.
The actual answer is more complex. Older versions of virtio (legacy) use in/out but the
current version (modern) can use memory read/write. Ideally, the DPDK virtio would only
ask for IOPL privilege if it needed it. The problem is that may need it during the negotiation
process. Someone should look into fixing this.
next prev parent reply other threads:[~2018-08-03 21:24 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1685797689.496737.1533140869394.ref@mail.yahoo.com>
2018-08-01 16:27 ` amit sehas
2018-08-03 21:24 ` Stephen Hemminger [this message]
2018-08-03 22:20 ` amit sehas
2018-08-05 14:35 ` amit sehas
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