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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.

  reply	other threads:[~2022-06-20  6:10 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-06-07 23:49 [PATCH 0/4] Improve documentation " Dmitry Kozlyuk
2022-06-07 23:49 ` [PATCH 1/4] usertools: add option to select hugetlbfs directory Dmitry Kozlyuk
2022-06-07 23:49 ` [PATCH 2/4] usertools: add option to change mount point owner Dmitry Kozlyuk
2022-06-08  0:00   ` Stephen Hemminger
2022-06-07 23:49 ` [PATCH 3/4] doc: give specific instructions for running as non-root 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
2022-06-17 11:25 ` [PATCH v2 0/4] Improve documentation for running as non-root Dmitry Kozlyuk
2022-06-17 11:25   ` [PATCH v2 1/4] usertools: add option to select hugetlbfs directory Dmitry Kozlyuk
2022-06-17 15:50     ` Bruce Richardson
2022-06-17 11:25   ` [PATCH v2 2/4] usertools: add option to change mount point owner Dmitry Kozlyuk
2022-06-17 15:53     ` Bruce Richardson
2022-06-20  5:43       ` Dmitry Kozlyuk
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
2022-06-24  8:48   ` [PATCH v3 0/5] Improve documentation for running as non-root Dmitry Kozlyuk
2022-06-24  8:48     ` [PATCH v3 1/5] usertools: add option to select hugetlbfs directory Dmitry Kozlyuk
2022-06-24  9:02       ` Bruce Richardson
2022-06-24  8:48     ` [PATCH v3 2/5] usertools: add option to change mount point owner Dmitry Kozlyuk
2022-06-24  9:04       ` Bruce Richardson
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
2022-06-24  8:48     ` [PATCH v3 5/5] doc: add note about running virtio-legacy as non-root Dmitry Kozlyuk
2022-06-24 13:19     ` [PATCH v4 0/5] Improve documentation for running " Dmitry Kozlyuk
2022-06-24 13:19       ` [PATCH v4 1/5] usertools: add option to select hugetlbfs directory Dmitry Kozlyuk
2022-06-24 13:19       ` [PATCH v4 2/5] usertools: add options to change mount point owner Dmitry Kozlyuk
2022-06-24 13:37         ` Bruce Richardson
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
2022-06-24 13:19       ` [PATCH v4 5/5] doc: add note about running virtio-legacy as non-root Dmitry Kozlyuk
2022-06-27  0:45       ` [PATCH v4 0/5] Improve documentation for running " Thomas Monjalon

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