On 10/3/14, 7:26 AM, "Zanussi, Tom" <[email protected]> wrote:
>On Thu, 2014-10-02 at 14:14 -0700, [email protected] wrote: >> From: Nitin A Kamble <[email protected]> >> >> Starting a new documentation section 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 section. >> >> Signed-off-by: Nitin A Kamble <[email protected]> >> --- >> README | 75 >>++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ >> 1 file changed, 75 insertions(+) >> >> diff --git a/README b/README >> index c829fdb..f633f36 100644 >> --- a/README >> +++ b/README >> @@ -83,3 +83,78 @@ 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. >> + >> + >> +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 >> + > >I took a quick look at the iucode-tool manpage, but didn't see anything >describing the signatures themselves or where to find them. It would be >helpful to the user of this feature to have some idea of where to look >to find them. Could you perhaps add a bit about that? Sure, this would help. Nitin > >Thanks, > >Tom > >> + 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
