[meta-intel] [PATCH 03/12] README.hardware: Documentation of hardware features

[Kamble, Nitin A]

On 10/2/14, 12:30 PM, "Darren Hart" <dvhart at linux.intel.com> wrote:

>On 10/2/14, 12:16, "Tom Zanussi" <tom.zanussi at intel.com> wrote:
>
>>On Thu, 2014-10-02 at 11:27 -0700, nitin.a.kamble at intel.com wrote:
>>> From: Nitin A Kamble <nitin.a.kamble at intel.com>
>>> 
>>> Starting a new documentation file to describe the layer specific
>>>hardware
>>> features. At this point the intel-ucode machine feature is described
>>>here.
>>> In the future more such features will be described in this file.
>>> 
>>> Signed-off-by: Nitin A Kamble <nitin.a.kamble at intel.com>
>>> ---
>>>  README.hardware | 88
>>>+++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>>
>>Cc:ing Paul, who had a review comment about this from last time:
>>
>>https://lists.yoctoproject.org/pipermail/meta-intel/2014-September/002614
>>.
>>html
>
>Thanks Tom, yes, I thought Paul's point was valid and needs to be
>addressed. It seems to me the layer README is a more appropriate location
>for things like new Machine Feature documentation.

If that is the preferred location, I will move this to the layer README.

Nitin

>
>--
>Darren
>
>>
>>Tom
>>
>>>  1 file changed, 88 insertions(+)
>>>  create mode 100644 README.hardware
>>> 
>>> diff --git a/README.hardware b/README.hardware
>>> new file mode 100644
>>> index 0000000..e27fb33
>>> --- /dev/null
>>> +++ b/README.hardware
>>> @@ -0,0 +1,88 @@
>>> +                    meta-intel Layer Hardware README
>>> +                    ================================
>>> +
>>> +This file gives details about using the meta-intel layer with the
>>>machines
>>> +supported in the layer. A full list of supported reference target
>>>machines
>>> +can be found by looking in the following directories:
>>> +
>>> +   conf/machine/
>>> +   meta-*/conf/machine/
>>> +   meta-isg/meta-*/conf/machine/
>>> +
>>> +The information in this file is also applicable to machines such as as
>>>minnow
>>> +which are defined in separate layers and utilize the meta-intel layer.
>>> +
>>> +
>>> +Machine Features in the meta-intel layer
>>> +========================================
>>> +
>>> +Many machine features are available in the oecore/poky layer for BSP
>>>use.
>>> +The meta-intel layer makes some additional machine features available
>>>for BSPs
>>> +using the meta-intel layer.
>>> +
>>> +Requirements
>>> +------------
>>> +
>>> +The additional machine features are only available when the meta-intel
>>>layer
>>> +is included in the build config, and the meta-intel.inc file is
>>>included in
>>> +the machine configuration of the interested BSP.
>>> +
>>> +To make these features available for your machine, you will need to:
>>> +
>>> +1. have a configuration line as seen below in the bblayers.conf
>>> +	BBLAYERS += "<local path>/meta-intel.git"
>>> +2. have the following line in the machine configuration
>>> +	require conf/machine/include/meta-intel.inc
>>> +
>>> +Once the above requirements are met, then the machine features
>>>provided by
>>> +the meta-intel layer will be available for the BSP use.
>>> +
>>> +Available Machine Features
>>> +--------------------------
>>> +
>>> +As of now the meta-intel layer provides the following list of machine
>>>features.
>>> +In the future, more machine features may be available in this list.
>>> +
>>> +* intel-ucode
>>> +
>>> +These machine features can be included by listing them in the
>>>MACHINE_FEATURES
>>> +variable in the machine configuration file.
>>> +
>>> +Details of the Machine Features
>>> +-------------------------------
>>> +
>>> +* intel-ucode: This feature provides microcode updating support for
>>>Intel
>>> +  processors. With the intel-ucode feature, images get complete
>>>support for
>>> +  updating the microcode on Intel processors. This feature enables
>>>microcode
>>> +  updating at early boot time by placing the microcode data files in
>>>the
>>> +  initrd image. It also puts the user land microcode updating tool
>>>iucode_tool
>>> +  and the microcode data file in the target images.
>>> +
>>> +  Q. Why to enable this microcode feature?
>>> +  A. Intel releases microcode updates to correct processor behavior as
>>> +     documented in the respective processor specification updates.
>>>While
>>> +     the regular approach to getting this microcode update 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 from the Linux OS. It provides an easy path for
>>>upgrading
>>> +     processor microcode without need of changing BIOS. Once the
>>>feature
>>> +     is enabled, it is also possible to update the existing images
>>>with
>>> +     newer microcode update in the future.
>>> +
>>> +  Q. How to bundle only specific microcodes in the target image?
>>> +  A. The Intel microcode data file released by Intel contains
>>>microcode
>>> +     updates for multiple processors. If the BSP image will be running
>>>only
>>> +     on a certain kind of processors, then the number of microcodes
>>>bundled in
>>> +     the target image can be filtered by specifying the
>>>UCODE_FILTER_SIGNATURES
>>> +     variable. A sequence of iucode-tool parameters are listed in the
>>> +     UCODE_FILTER_SIGNATURES variable to filter the microcodes from
>>>the
>>> +     microcode data file. For more information on these parameters
>>>refer to
>>> +     the iucode-tool manual page, which can be seen over here:
>>> +       http://manned.org/iucode-tool
>>> +
>>> +  Q. When to not enable this microcode feature?
>>> +  A. The microcode datafile and the associated tools take small (few
>>>KB)
>>> +     space on the target image. The BSPs which are highly sensitive to
>>>the
>>> +     target image size, which are not experiencing any microcode
>>>related issues,
>>> +     may consider not enabling this feature to save the target image
>>>foot print.
>>> +
>>
>>
>>
>
>
>-- 
>Darren Hart
>Intel Open Source Technology Center
>
>
>