Re: [dpdk-dev] [PATCH 2/2] doc: update programmers guide for uio_pci_generic

["Iremonger, Bernard" <bernard.iremonger@intel.com>]

> -----Original Message-----
> From: Richardson, Bruce
> Sent: Wednesday, February 25, 2015 12:28 PM
> To: Iremonger, Bernard
> Cc: dev@dpdk.org
> Subject: Re: [dpdk-dev] [PATCH 2/2] doc: update programmers guide for uio_pci_generic
> 
> On Wed, Feb 25, 2015 at 12:19:10PM +0000, Iremonger, Bernard wrote:
> >
> >
> > > -----Original Message-----
> > > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Bruce
> > > Richardson
> > > Sent: Tuesday, February 24, 2015 4:28 PM
> > > To: dev@dpdk.org
> > > Subject: [dpdk-dev] [PATCH 2/2] doc: update programmers guide for
> > > uio_pci_generic
> > >
> > > Since DPDK now has support for the in-tree uio_pci_generic driver,
> > > update the programmers guide document to reference this module, and
> > > to use it in preference to the igb_uio driver, which is DPDK- specific.
> > >
> > > Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
> > > ---
> > >  doc/guides/prog_guide/env_abstraction_layer.rst                  | 8 ++++----
> > >  doc/guides/prog_guide/intel_dpdk_xen_based_packet_switch_sol.rst | 6 +++---
> > >  doc/guides/prog_guide/kernel_nic_interface.rst                   | 2 +-
> > >  doc/guides/prog_guide/poll_mode_drv_emulated_virtio_nic.rst      | 8 ++++----
> > >  doc/guides/prog_guide/poll_mode_drv_paravirtual_vmxnets_nic.rst  |
> > > 2 +-
> > >  5 files changed, 13 insertions(+), 13 deletions(-)
> > >
> > > diff --git a/doc/guides/prog_guide/env_abstraction_layer.rst
> > > b/doc/guides/prog_guide/env_abstraction_layer.rst
> > > index 231e266..b5321c3 100644
> > > --- a/doc/guides/prog_guide/env_abstraction_layer.rst
> > > +++ b/doc/guides/prog_guide/env_abstraction_layer.rst
> > > @@ -66,7 +66,7 @@ EAL in a Linux-userland Execution Environment
> > >  ---------------------------------------------
> > >
> > >  In a Linux user space environment, the DPDK application runs as a
> > > user-space application using the pthread library.
> > > -PCI information about devices and address space is discovered
> > > through the /sys kernel interface and through a module called igb_uio.
> > > +PCI information about devices and address space is discovered
> > > +through the /sys kernel interface and
> > > through kernel modules such as uio_pci_generic, or igb_uio.
> > >  Refer to the UIO: User-space drivers documentation in the Linux
> > > kernel. This memory is mmap'd in the application.
> > >
> > >  The EAL performs physical memory allocation using mmap() in
> > > hugetlbfs (using huge page sizes to increase performance).
> > > @@ -134,10 +134,10 @@ PCI Access
> > >  ~~~~~~~~~~
> > >
> > >  The EAL uses the /sys/bus/pci utilities provided by the kernel to scan the content on the PCI bus.
> > > -
> > > -To access PCI memory, a kernel module called igb_uio provides a
> > > /dev/uioX device file
> > > +To access PCI memory, a kernel module called uio_pci_generic
> > > +provides a /dev/uioX device file and resource files in /sys
> > >  that can be mmap'd to obtain access to PCI address space from the application.
> > > -It uses the uio kernel feature (userland driver).
> > > +The DPDK-specific igb_uio module can also be used for this. Both
> > > +drivers use the uio kernel feature
> > > (userland driver).
> > >
> > >  Per-lcore and Shared Variables
> > >  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > > diff --git
> > > a/doc/guides/prog_guide/intel_dpdk_xen_based_packet_switch_sol.rst
> > > b/doc/guides/prog_guide/intel_dpdk_xen_based_packet_switch_sol.rst
> > > index 1f1e04f..a0dd959 100644
> > > ---
> > > a/doc/guides/prog_guide/intel_dpdk_xen_based_packet_switch_sol.rst
> > > +++ b/doc/guides/prog_guide/intel_dpdk_xen_based_packet_switch_sol.r
> > > +++ st
> > > @@ -306,12 +306,12 @@ Building and Running the Switching Backend
> > >          Refer to the *DPDK Getting Started Guide* for more
> > > information on memory management in the DPDK.
> > >          In the above command, 4 GB memory is reserved (2048 of 2 MB pages) for DPDK.
> > >
> > > -#.  Load igb_uio and bind one Intel NIC controller to igb_uio:
> > > +#.  Load uio_pci_generic and bind one Intel NIC controller to it:
> > >
> > >      .. code-block:: console
> > >
> > > -        insmod x86_64-native-linuxapp-gcc/kmod/igb_uio.ko
> > > -        python tools/dpdk_nic_bind.py -b igb_uio 0000:09:00:00.0
> >
> >
> > Hi Bruce,
> >
> > Should the information about igb_uio be retained alongside the new information about
> uio_pci_generic?
> >
> While the answer may not be as clear-cut as with the GSG, why would be bother covering both here.
> We already ignore VFIO in these examples.
> 
> /Bruce

Hi Bruce,

The method of loading is different for both modules, igb_uio uses insmod and uio_pci_generic uses modprobe.
It would be useful to retain this igb_uio information. Maybe vfio information should be added too.
This comment also applies to the GSG,  the differences need to be documented.

Regards,

Bernard.