Re: [dpdk-dev] [PATCH 1/2] doc/linux_gsg: clarify instructions on running as non-root

["Burakov, Anatoly" <anatoly.burakov@intel.com>]

On 24-Aug-20 6:08 PM, Bruce Richardson wrote:
> On Mon, Aug 24, 2020 at 04:45:00PM +0100, Anatoly Burakov wrote:
>> The current instructions are slightly out of date when it comes to
>> providing information about setting up the system for using DPDK as
>> non-root, so update them.
>>
>> Cc: stable@dpdk.org
>>
>> Signed-off-by: Anatoly Burakov <anatoly.burakov@intel.com>
>> ---
>>   doc/guides/linux_gsg/enable_func.rst | 54 ++++++++++++++++++++--------
>>   1 file changed, 39 insertions(+), 15 deletions(-)
>>
>> diff --git a/doc/guides/linux_gsg/enable_func.rst b/doc/guides/linux_gsg/enable_func.rst
>> index b2bda80bb7..78b0f7c012 100644
>> --- a/doc/guides/linux_gsg/enable_func.rst
>> +++ b/doc/guides/linux_gsg/enable_func.rst
>> @@ -58,22 +58,34 @@ The application can then determine what action to take, if any, if the HPET is n
>>       if any, and on what is available on the system at runtime.
>>   
>>   Running DPDK Applications Without Root Privileges
>> ---------------------------------------------------------
>> +-------------------------------------------------
>>   
>> -.. note::
>> +In order to run DPDK as non-root, the following Linux filesystem objects'
>> +permissions should be adjusted to ensure that the Linux account being used to
>> +run the DPDK application has access to them:
>>   
>> -    The instructions below will allow running DPDK as non-root with older
>> -    Linux kernel versions. However, since version 4.0, the kernel does not allow
>> -    unprivileged processes to read the physical address information from
>> -    the pagemaps file, making it impossible for those processes to use HW
>> -    devices which require physical addresses
>> +*   All directories which serve as hugepage mount points, for example, ``/dev/hugepages``
>>   
>> -Although applications using the DPDK use network ports and other hardware resources directly,
>> -with a number of small permission adjustments it is possible to run these applications as a user other than "root".
>> -To do so, the ownership, or permissions, on the following Linux file system objects should be adjusted to ensure that
>> -the Linux user account being used to run the DPDK application has access to them:
>> +*   If the HPET is to be used,  ``/dev/hpet``
>>   
>> -*   All directories which serve as hugepage mount points, for example,   ``/mnt/huge``
>> +When running as non-root user, there may be some additional resource limits
>> +that are imposed by the system. Specifically, the following resource limits may
>> +need to be adjusted in order to ensure normal DPDK operation:
>> +
>> +* RLIMIT_LOCKS (number of file locks that can be held by a process)
>> +
>> +* RLIMIT_NOFILE (number of open file descriptors that can be held open by a process)
>> +
>> +* RLIMIT_MEMLOCK (amount of pinned pages the process is allowed to have)
>> +
>> +The above limits can usually be adjusted by editing
>> +``/etc/security/limits.conf`` file, and rebooting.
>> +
>> +Additionally, depending on which kernel driver is in use, the relevant
>> +resources also should be accessible by the user running the DPDK application.
>> +
>> +For ``igb_uio`` or ``uio_pci_generic`` kernel drivers, the following Linux file
>> +system objects' permissions should be adjusted:
>>   
>>   *   The userspace-io device files in  ``/dev``, for example,  ``/dev/uio0``, ``/dev/uio1``, and so on
>>   
>> @@ -82,11 +94,23 @@ the Linux user account being used to run the DPDK application has access to them
>>          /sys/class/uio/uio0/device/config
>>          /sys/class/uio/uio0/device/resource*
>>   
>> -*   If the HPET is to be used,  ``/dev/hpet``
>> -
>>   .. note::
>>   
>> -    On some Linux installations, ``/dev/hugepages``  is also a hugepage mount point created by default.
>> +    The instructions above will allow running DPDK with ``igb_uio`` driver as
>> +    non-root with older Linux kernel versions. However, since version 4.0, the
>> +    kernel does not allow unprivileged processes to read the physical address
>> +    information from the pagemaps file, making it impossible for those
>> +    processes to be used by non-privileged users. In such cases, using the VFIO
>> +    driver is recommended.
>> +
>> +For ``vfio-pci`` kernel driver, the following Linux file system objects'
>> +permissions should be adjusted:
>> +
>> +* The VFIO device file , ``/dev/vfio/vfio``
>> +
>> +* The directories under ``/dev/vfio`` that correspond to IOMMU group numbers of
>> +  devices intended to be used by DPDK, for example, ``/dev/vfio/50``
>> +
>>   
> Since we'd very much prefer in all cases people to use VFIO, I think the
> VFIO instructions should come first.
> Otherwise the text itself reads fine to me.

OK, will fix in v2.

> 
> /Bruce
> 


-- 
Thanks,
Anatoly