meta-intel
==========

This README file contains information on building and booting
meta-intel BSP layers.  Please see the corresponding sections below
for details.


Yocto Project Compatible
========================

The BSPs contained in this layer are compatible with the Yocto Project
as per the requirements listed here:

  https://www.yoctoproject.org/webform/yocto-project-compatible-registration


Dependencies
============

This layer depends on:

  URI: git://git.openembedded.org/bitbake
  branch: master

  URI: git://git.openembedded.org/openembedded-core
  layers: meta
  branch: master


Table of Contents
=================

  I. Overview
  II. Building and booting meta-intel BSP layers
     a. Building the intel-common BSP layers
     b. Booting the intel-common BSP images
  III. Technical Miscellany
     Benefits of using meta-intel
     The intel-common kernel package architecture
     Intel-specific machine features
  IV. Tested Hardware
  V.  Guidelines for submitting patches


I. Overview
===========

This is the location for Intel-maintained BSPs.

For details on the intel-common, see the information below.

For all others, please see the README files contained in the
individual BSP layers for BSP-specific information.

If you have problems with or questions about a particular BSP, please
contact the maintainer listed in the MAINTAINERS file directly (cc:ing
the Yocto mailing list puts it in the archive and helps other people
who might have the same questions in the future), but please try to do
the following first:

  - look in the Yocto Project Bugzilla
    (http://bugzilla.yoctoproject.org/) to see if a problem has
    already been reported

  - look through recent entries of the meta-intel
    (https://lists.yoctoproject.org/pipermail/meta-intel/) and Yocto
    (https://lists.yoctoproject.org/pipermail/yocto/) mailing list
    archives to see if other people have run into similar problems or
    had similar questions answered.

If you believe you have encountered a bug, you can open a new bug and
enter the details in the Yocto Project Bugzilla
(http://bugzilla.yoctoproject.org/).  If you're relatively certain
that it's a bug against the BSP itself, please use the 'Yocto Project
Components: BSPs | meta-intel' category for the bug; otherwise, please
submit the bug against the most likely category for the problem - if
you're wrong, it's not a big deal and the bug will be recategorized
upon triage.


II. Building and booting meta-intel BSP layers
==============================================

The following sections contain information on building and booting the
BSPs contained in the meta-intel layer.

Note that these instructions specifically cover the intel-common, which
may or may not be applicable to other BSPs contained in this layer - if
a given BSP contains its own README, that version should be used instead,
and these instructions can be ignored.

a. Building the intel-common BSP layers
-------------------------------------------------

In order to build an image with BSP support for a given release, you
need to download the corresponding BSP tarball from the 'Board Support
Package (BSP) Downloads' page of the Yocto Project website (or
equivalently, check out the appropriate branch from the meta-intel git
repository, see below).  For the intel-common BSPs, those tarballs would
correspond to the following choices in the BSP downloads section:

 - Intel-core2-32 Intel® Common Core BSP (Intel-core2-32)
 - Intel-corei7-64 Intel® Common Core BSP (Intel-corei7-64)

The intel-* BSPs, also known as the intel-common BSPs, provide a few
carefully selected tune options and generic hardware support to cover
the majority of current Intel CPUs and devices. The naming follows the
convention of intel-<TUNE>-<BITS>, where TUNE is the gcc cpu-type
(used with mtune and march typically) and BITS is either 32 bit or 64
bit.

Having done that, and assuming you extracted the BSP tarball contents
at the top-level of your yocto build tree, you can build a BSP image
by adding the location of the meta-intel layer to bblayers.conf e.g.:

  yocto/meta-intel \

To enable a particular machine, you need to add a MACHINE line naming
the BSP to the local.conf file:

  MACHINE ?= "xxx"

where 'xxx' is replaced by one of the following BSP names:

 - intel-core2-32

   This BSP is optimized for the Core2 family of CPUs as well as all
   Atom CPUs prior to the Silvermont core.

 - intel-corei7-64

   This BSP is optimized for Nehalem and later Core and Xeon CPUs as
   well as Silvermont and later Atom CPUs, such as the Baytrail SoCs.

You should then be able to build an image as such:

  $ source oe-init-build-env
  $ bitbake core-image-sato

At the end of a successful build, you should have an image that
you can boot from a USB flash drive (see instructions on how to do
that below, in the section 'Booting the intel-common BSP images').

As an alternative to downloading the BSP tarball, you can also work
directly from the meta-intel git repository.  For each BSP in the
'meta-intel' repository, there are multiple branches, one
corresponding to each major release starting with 'laverne' (0.90), in
addition to the latest code which tracks the current master (note that
not all BSPs are present in every release).  Instead of extracting
a BSP tarball at the top level of your yocto build tree, you can
equivalently check out the appropriate branch from the meta-intel
repository at the same location.

b. Booting the intel-common BSP images
--------------------------------------

If you've built your own image, either from the downloaded BSP layer
or from the meta-intel git repository, you'll find the bootable
image in the build/tmp/deploy/images/xxx directory, where again
'xxx' refers to the machine name used in the build.

Under Linux, insert a USB flash drive.  Assuming the USB flash drive
takes device /dev/sdf, use dd to copy the image to it.  Before the image
can be burned onto a USB drive, it should be un-mounted. Some Linux distros
may automatically mount a USB drive when it is plugged in. Using USB device
/dev/sdf as an example, find all mounted partitions:

    $ mount | grep sdf

and un-mount those that are mounted, for example:

    $ umount /dev/sdf1
    $ umount /dev/sdf2

Now burn the image onto the USB drive:

    $ sudo dd if=core-image-sato-intel-corei7-64.wic of=/dev/sdf status=progress
    $ sync
    $ eject /dev/sdf

This should give you a bootable USB flash device.  Insert the device
into a bootable USB socket on the target, and power on.  This should
result in a system booted to the Sato graphical desktop.

If you want a terminal, use the arrows at the top of the UI to move to
different pages of available applications, one of which is named
'Terminal'.  Clicking that should give you a root terminal.

If you want to ssh into the system, you can use the root terminal to
ifconfig the IP address and use that to ssh in.  The root password is
empty, so to log in type 'root' for the user name and hit 'Enter' at
the Password prompt: and you should be in.

If you find you're getting corrupt images on the USB (it doesn't show
the syslinux boot: prompt, or the boot: prompt contains strange
characters), try doing this first:

    $ dd if=/dev/zero of=/dev/sdf bs=1M count=512

III. Technical Miscellany
=========================

Benefits of using meta-intel
----------------------------

Using meta-intel has the following benefits over a generic BSP:

tune flags
++++++++++
intel-* MACHINEs each have different compilation flags appropriate for their
targeted hardware sets. intel-corei7-64 has tune flags appropriate for modern
64-bit Intel Core i microarchitecture, and includes instruction sets up to
SSE4.2. intel-core2-32 has tune flags appropriate for legacy 32-bit Intel Core2
microarchitecture, and includes instruction sets up to SSE3.

linux-intel kernel
++++++++++++++++++
The linux-intel kernel is an initiative to bring better Intel(R) hardware
support to the current LTS linux kernel. It contains a base LTS kernel with
additional backports from upstream Intel drivers. In addition, a default kernel
config containing most features found on Intel boards is supplied via the
yocto-kernel-cache.

graphics stack
++++++++++++++
Meta-intel provides the latest Intel Graphics Linux Stack drivers to support
Intel hardware as defined by the https://01.org/linuxgraphics.

Other software
++++++++++++++
  * intel ucode - provides the latest microcode updates for Intel processors

  * thermald - which proactively controls thermal, using P-states, T-states, and
the Intel power clamp driver.
(https://01.org/linux-thermal-daemon/documentation/introduction-thermal-daemon)

The intel-common kernel package architecture
--------------------------------------------

These BSPs use what we call the intel-common Linux kernel package
architecture. This includes core2-32-intel-common and
corei7-64-intel-common. These kernel packages can also be used by any
of the BSPs in meta-intel that choose to include the
intel-common-pkgarch.inc file.

To minimize the proliferation of vendor trees, reduce the sources we
must support, and consolidate QA efforts, all BSP maintainers are
encouraged to make use of the intel-common Linux kernel package
architecture.

Intel-specific machine features
-------------------------------

The meta-intel layer makes some additional machine features available
to BSPs.  These machine features can be used in a BSP layer in the
same way that machine features are used in other layers based on
oe-core, via the MACHINE_FEATURES variable.

Requirements
++++++++++++

The meta-intel-specific machine features are only available to a BSP
when the meta-intel layer is included in the build configuration, and
the meta-intel.inc file is included in the machine configuration of
that BSP.

To make these features available for your machine, you will need to:

  1. include a configuration line such as the below in bblayers.conf
       BBLAYERS += "<local path>/meta-intel"
  2. include the following line in the machine configuration file
       require conf/machine/include/meta-intel.inc

Once the above requirements are met, the machine features provided by
the meta-intel layer will be available for the BSP to use.

Available machine features
++++++++++++++++++++++++++

Currently, the meta-intel layer makes the following set of
Intel-specific machine features available:

  * intel-ucode

These machine features can be included by listing them in the
MACHINE_FEATURES variable in the machine configuration file.  For
example:

    MACHINE_FEATURES += "intel-ucode"

Machine feature details
+++++++++++++++++++++++

 * intel-ucode

    This feature provides support for microcode updates to Intel
    processors.  The intel-ucode feature runs at early boot and uses
    the microcode data file added by the feature into the BSP's
    initrd.  It also puts the userland microcode-updating tool,
    iucode_tool, into the target images along with the microcode data
    file.

    Q. Why might a user want to enable the intel-ucode feature?

    A. Intel releases microcode updates to correct processor behavior
       as documented in the respective processor specification
       updates.  While the normal approach to getting such microcode
       updates is via a BIOS upgrade, this can be an administrative
       hassle and not always possible in the field.  The intel-ucode
       feature enables the microcode update capability present in the
       Linux kernel.  It provides an easy path for upgrading processor
       microcode without the need to change the BIOS.  If the feature
       is enabled, it is also possible to update the existing target
       images with a newer microcode update in the future.

    Q. How would a user bundle only target-specific microcode in the
       target image?

    A. The Intel microcode data file released by Intel contains
       microcode updates for multiple processors.  If the BSP image is
       meant to run on only a certain subset of processor types, a
       processor-specific subset of microcode can be bundled into the
       target image via the UCODE_FILTER_PARAMETERS variable.  This
       works by listing a sequence of iucode-tool parameters in the
       UCODE_FILTER_PARAMETERS variable, which in this case will
       select only the specific microcode relevant to the BSP.  For
       more information on the underlying parameters refer to the
       iucode-tool manual page at http://manned.org/iucode-tool

       To define a set of parameters for microcode-filtering via the
       UCODE_FILTER_PARAMETERS variable, one needs to identify the
       cpuid signatures of all the processors the BSP is meant to run
       on.  One way to determine the cpuid signature for a specific
       processor is to build and run an intel-ucode-feature-enabled
       image on the target hardware, without first assigning any value
       to the UCODE_FILTER_PARAMETERS variable, and then once the
       image is booted, run the "ucode_tool -S" command to have the
       ucode tool scan the system for processor signatures.  These
       signatures can then be used in the UCODE_FILTER_PARAMETERS
       variable in conjunction with -s parameter.  For example, for
       the fri2 BSP, the cpuid can be determined as such:

         [root@fri2 ~]# iucode_tool -S
         iucode_tool: system has processor(s) with signature 0x00020661

       Given that output, a suitable UCODE_FILTER_PARAMETERS variable
       definition could be specified in the machine configuration as
       such:

         UCODE_FILTER_PARAMETERS = "-s 0x00020661"

    Q. Are there any reasons a user might want to disable the
       intel-ucode feature?

    A. The microcode data file and associated tools occupy a small
       amount of space (a few KB) on the target image.  BSPs which are
       highly sensitive to target image size and which are not
       experiencing microcode-related issues might consider not
       enabling this feature.


IV. Tested Hardware
===================

The following undergo regular basic testing with their respective MACHINE types.
Note that both 64-bit and 32-bit firmware is available for the MinnowBoard
Turbot, so it is tested against both intel-corei7-64 and intel-core2-32.

intel-corei7-64:
    NUC6i5SYH
    MinnowBoard Turbot

intel-core2-32:
    MinnowBoard Turbot


V. Guidelines for submitting patches
====================================

Please submit any patches against meta-intel BSPs to the meta-intel
mailing list (meta-intel@yoctoproject.org).  Also, if your patches are
available via a public git repository, please also include a URL to
the repo and branch containing your patches as that makes it easier
for maintainers to grab and test your patches.

There are patch submission scripts available that will, among other
things, automatically include the repo URL and branch as mentioned.
Please see the Yocto Project Development Manual sections entitled
'Using Scripts to Push a Change Upstream and Request a Pull' and
'Using Email to Submit a Patch' for details.

Regardless of how you submit a patch or patchset, the patches should
at minimum follow the suggestions outlined in the 'Submitting a Change
to the Yocto Project' section in the Yocto Project Development Manual.
Specifically, they should:

  - Include a 'Signed-off-by:' line.  A commit can't legally be pulled
    in without this.

  - Provide a single-line, short summary of the change.  This short
    description should be prefixed by the BSP or recipe name, as
    appropriate, followed by a colon.  Capitalize the first character
    of the summary (following the colon).

  - For the body of the commit message, provide detailed information
    that describes what you changed, why you made the change, and the
    approach you used.

  - If the change addresses a specific bug or issue that is associated
    with a bug-tracking ID, include a reference to that ID in your
    detailed description in the following format: [YOCTO #<bug-id>].

  - Pay attention to line length - please don't allow any particular
    line in the commit message to stretch past 72 characters.

  - For any non-trivial patch, provide information about how you
    tested the patch, and for any non-trivial or non-obvious testing
    setup, provide details of that setup.

Doing a quick 'git log' in meta-intel will provide you with many
examples of good example commits if you have questions about any
aspect of the preferred format.

The meta-intel maintainers will do their best to review and/or pull in
a patch or patchset within 24 hours of the time it was posted.  For
larger and/or more involved patches and patchsets, the review process
may take longer.

Please see the meta-intel/MAINTAINERS file for the list of maintainers
and their specific areas; it's also a good idea to cc: the specific
maintainer, if applicable.