[dpdk-dev] thoughts on DPDK after a few days of reading sources

Christian Ehrhardt christian.ehrhardt at canonical.com
Wed Feb 17 10:35:03 CET 2016


Hi Alejandro,
thanks for the heads up - to make sure I got your correctly I assume you
refer to:

[1]: dpdk:
http://dpdk.org/browse/dpdk/commit/?id=e61512e4066740847ced4a85ee9c3334b511468f
[2]: kernel:
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=033291eccbdb
[3]: kernel:
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=ae5515d66362b9d96cdcfce504567f0b8b7bd83e
[4]: kenrel:
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=03a76b60f8ba27974e2d252bc555d2c103420e15

It seems we will be shipping DPDK 2.2 and Kernel 4.4 with the next release
(no commitment being made).
[1] is not in DPDK 2.2, so it won't be supported right away. If it can be
used without [1] I wouldn't have realized that yet.
But also in the kernel it is not only disabled by default - in fact the
code itself got removed [3] and only later back into 4.5 [4].
I guess, to really activate, exploit, test and eventually support it - it
would be up to an explicit request to do so which can then be evaluated
against the risks.

IMHO I think we have to wait and see how it will be workin in DPDK >=16.x
and Kernel >=4.5 this kind of referring to [3] "... so rather than support
an unproven kernel interface revert it and revisit ...".

Thanks for the heads up Alejandro, I didn't really think much about it
before - I'll revisit it every now and then to see how development around
it goes on.


Christian Ehrhardt
Software Engineer, Ubuntu Server
Canonical Ltd

On Thu, Feb 11, 2016 at 12:58 PM, Alejandro Lucero <
alejandro.lucero at netronome.com> wrote:

> Hi Seth,
>
> I do not know if you and Ubuntu know about the kernel VFIO no-iommu mode
> which DPDK will use in the future (then getting rid of UIO drives).
>
> This implies distributions enabling that kernel VFIO mode which is not
> enable by default as it is a security issue.
>
> It would be good to know which is the Ubuntu position regarding this issue
> and if there are any date or plan for supporting this.
>
> Thanks
>
> On Thu, Feb 11, 2016 at 7:58 AM, Thomas Monjalon <
> thomas.monjalon at 6wind.com>
> wrote:
>
> > Hi,
> >
> > 2016-02-10 19:05, Seth Arnold:
> > > I've taken some notes while reading the sources; I'm sharing them in
> the
> > > hopes that it's useful: on the one hand my fresh eyes may spot things
> > that
> > > you've overlooked, on the other hand your familiarity with the code
> means
> > > that you're better suited to judge what I've found.
> >
> > Thanks for taking time and sharing, it's very valuable.
> >
> > > - shellcheck reports extensive cases of forgotten quotes to prevent
> word
> > >   splitting or globbing, potentially unused variables, error-prone
> printf
> > >   formatting. The scripts that are going to be used at runtime should
> be
> > >   fixed:
> > >   - ./debian/dpdk-init
> > >   - ./debian/dpdk.init
> >
> > These files are not in the tree. Should they?
> >
> > > - ./drivers/net/cxgbe/cxgbe_ethdev.c eth_cxgbe_dev_init() memory leak
> in
> > >   out_free_adapter: that doesn't free adapter
> > > - ./drivers/net/virtio/virtio_ethdev.c virtio_set_multiple_queues()
> calls
> > >   virtio_send_command(), which performs:
> > >   memcpy(vq->virtio_net_hdr_mz->addr, ctrl, sizeof(struct
> > virtio_pmd_ctrl));
> > >   This copies a potentially huge amount of uninitialized data into
> ->addr
> > >   because the struct virtio_pmd_ctrl ctrl was not zeroed before being
> > >   passed. How much of this data leaves the system? Does this require a
> > >   CVE?
> >
> > We are not used to open a CVE.
> >
> > [...]
> > >   It's nearly impossible to solve issues without error reporting. Good
> > >   error reporting saves admins time and money.
> >
> > Until now, the errors were reported on the list and most often fixed
> > quickly.
> > While I agree we need a more formal process (a bug tracker), I think we
> > must
> > be noticed of new bugs on the mailing list.
> > Since nobody was against the bugzilla proposal, a deployment will be
> > planned.
> >         http://dpdk.org/ml/archives/dev/2015-August/023012.html
> >
>


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