From: Dmitry Kozlyuk <dkozlyuk@nvidia.com>
To: Bruce Richardson <bruce.richardson@intel.com>
Cc: "dev@dpdk.org" <dev@dpdk.org>,
"stable@dpdk.org" <stable@dpdk.org>,
Anatoly Burakov <anatoly.burakov@intel.com>
Subject: RE: [PATCH v2 3/4] doc: give specific instructions for running as non-root
Date: Mon, 20 Jun 2022 06:10:37 +0000 [thread overview]
Message-ID: <BL1PR12MB5945905A50DF85C76952CAF9B9B09@BL1PR12MB5945.namprd12.prod.outlook.com> (raw)
In-Reply-To: <Yqyt+7wPHLR4cqKb@bricha3-MOBL.ger.corp.intel.com>
> From: Bruce Richardson <bruce.richardson@intel.com>
> Sent: Friday, June 17, 2022 7:38 PM
> > [...]
> > +If the driver requires using physical addresses (PA),
> > +the executable file must be granted additional capabilities:
> > +
> > +* ``SYS_ADMIN`` to read ``/proc/self/pagemaps``
> > +* ``IPC_LOCK`` to lock hugepages in memory
>
> Are either of these necessary if using vfio-pci and VA mode? I have
> seen it previously reported that IPC_LOCK is necessary for IOMMU
> memory mapping for DMA - at least for docker containers - so I'd
> like it confirmed that we don't need them in the in-memory case
> running on the host. If I get the chance I'll try double-checking
> by testing myself.
Sorry, I don't have a physical device using vfio-pci to check.
MLX5 that I have tested doesn't need these capabilities,
but it locks memory from the kernel side.
Note that --in-memory doesn't imply --iova-mode=va.
>
> > +
> > +.. code-block:: console
> > +
> > + setcap cap_ipc_lock,cap_sys_admin+ep <executable>
> > +
> > +If physical addresses are not accessible,
> > +the following message will appear during EAL initialization::
> > +
> > + EAL: rte_mem_virt2phy(): cannot open /proc/self/pagemap:
> Permission denied
> > +
> > +It is harmless in case PA are not needed.
> > +
>
> While this is probably worth having in the doc, I think we should
> really
> include a note here about using vfio-pci rather than uio and therefore
> not
> needing physical addresses.
A note won't harm. There are also non-PCI devices, though.
> > +For ``virtio`` PMD in legacy mode, ``SYS_RAWIO`` capability is
> required
> > +for ``iopl()`` call to enable access to PCI IO ports.
> >
>
> How "legacy" is legacy-mode? Is it still likely in widespread use that
> we need this?
I don't really know.
The spec says that legacy support is optional
(2.2.3 Legacy Interface: A Note on Feature Bits) and it aims
to reduce the chance of a legacy driver attempting to drive the device
(4.1.2.1 Device Requirements: PCI Device Discovery).
OTOH, DPDK supports it and requirements must be documented.
I can add a line suggesting to use modern virtio,
but also don't mind removing this.
I'll address skipped comments in v3, thanks.
next prev parent reply other threads:[~2022-06-20 6:10 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20220607234949.2311884-1-dkozlyuk@nvidia.com>
2022-06-07 23:49 ` [PATCH " Dmitry Kozlyuk
2022-06-08 0:03 ` Stephen Hemminger
2022-06-07 23:49 ` [PATCH 4/4] doc: update instructions for running as non-root for MLX5 Dmitry Kozlyuk
2022-06-08 0:13 ` Stephen Hemminger
2022-06-17 11:26 ` Dmitry Kozlyuk
[not found] ` <20220617112508.3823291-1-dkozlyuk@nvidia.com>
2022-06-17 11:25 ` [PATCH v2 3/4] doc: give specific instructions for running as non-root Dmitry Kozlyuk
2022-06-17 16:38 ` Bruce Richardson
2022-06-20 6:10 ` Dmitry Kozlyuk [this message]
2022-06-20 8:37 ` Bruce Richardson
2022-06-24 8:49 ` Dmitry Kozlyuk
2022-06-17 11:25 ` [PATCH v2 4/4] doc: update instructions for running as non-root for MLX5 Dmitry Kozlyuk
[not found] ` <20220624084817.63145-1-dkozlyuk@nvidia.com>
2022-06-24 8:48 ` [PATCH v3 3/5] doc: give specific instructions for running as non-root Dmitry Kozlyuk
2022-06-24 9:09 ` Bruce Richardson
2022-06-24 8:48 ` [PATCH v3 4/5] doc: update instructions for running as non-root for MLX5 Dmitry Kozlyuk
[not found] ` <20220624131956.75160-1-dkozlyuk@nvidia.com>
2022-06-24 13:19 ` [PATCH v4 3/5] doc: give specific instructions for running as non-root Dmitry Kozlyuk
2022-06-24 13:19 ` [PATCH v4 4/5] doc: update instructions for running as non-root for MLX5 Dmitry Kozlyuk
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