On Thu, 2014-10-02 at 11:27 -0700, [email protected] wrote: > From: Nitin A Kamble <[email protected]> > > 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 <[email protected]> > --- > 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 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. > + -- _______________________________________________ meta-intel mailing list [email protected] https://lists.yoctoproject.org/listinfo/meta-intel
