Difference between revisions of "OpenPOWER Firmware"

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'''OpenPOWER Firmware''' is an open-source alternative to OpenFirmware and proprietary IBM firmware used on Power machines.<ref>Kerr, Jeremy. [https://lca2015.linux.org.au/schedule/30305/view_talk OpenPOWER: building an open-source software stack from bare metal]. LCA 2015</ref> It is a general name for many separate pieces of software used to start recent Power Architecture chips made by IBM.<ref>Smith, Stewart. [http://lca2016.linux.org.au/schedule/30215/view_talk Adventures in OpenPOWER Firmware]. LCA 2016</ref>
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'''OpenPOWER Firmware''' is an open-source alternative to OpenFirmware and proprietary IBM firmware used on Power machines.<ref>Kerr, Jeremy. [https://lca2015.linux.org.au/schedule/30305/view_talk OpenPOWER: building an open-source software stack from bare metal]. LCA 2015 - [https://www.youtube.com/watch?v=DigNr08GVss video on YouTube]</ref> It is a general name for many separate pieces of software used to start recent Power Architecture chips made by IBM.<ref>Smith, Stewart. [http://lca2016.linux.org.au/schedule/30215/view_talk Adventures in OpenPOWER Firmware]. LCA 2016 - [https://www.youtube.com/watch?v=a4XGvssR-ag video on YouTube]</ref>
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[[OpenBMC|OpenBMC]] is a separate project that creates firmware for the [[BMC|Baseboard Management Controller]].
  
 
== Components ==
 
== Components ==
  
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* [[Self-Boot Engine|Self-Boot Engine]] (SBE) code - loads Hostboot an a CPU core
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{| class="wikitable sortable"
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* [[Hostboot|Hostboot]] - loads Skiboot
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! Firmware
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* [[Skiboot|Skiboot]] - implements [[OpenPOWER Abstraction Layer|OpenPOWER Abstraction Layer]] (OPAL), loads Petitboot, and loads OCC code into the OCC core
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! Executed on
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* [[Petitboot|Petitboot]] - loads the operating system
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! Loaded from
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* [[On-Chip Controller|On-Chip Controller]] (OCC) code - controls thermal regulation on the chip
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! Function
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|-
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| SBE - OTPROM
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[https://git.raptorcs.com/git/talos-sbe/tree/src/boot/otprom_init.S Source]
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| [[Self-Boot Engine|SBE]] core (on CPU)
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| [[OTPROM|OTPROM]] (on CPU die)
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| The portion of [[Self-Boot Engine|Self-Boot Engine]] (SBE) firmware permanently written via eFuses into the POWER9 silicon's OTPROM
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* very first instructions executed
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* loads remaining SBE firmware from SEEPROM into SBE core
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|-
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| SBE - SEEPROM
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[https://git.raptorcs.com/git/talos-sbe/tree/ Source]
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| [[Self-Boot Engine|SBE]] core (on CPU)
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| SBE [[SEEPROM|SEEPROM]] (on CPU)
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| The portion of [[Self-Boot Engine|Self-Boot Engine]] (SBE) firmware run from rewritable [[SEEPROM|SEEPROM]]
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* initialises CPU core
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* loads Hostboot Bootloader
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* backup copy stored on PNOR SPI Flash, used to stage SBE firmware updates
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|-
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| Hostboot Bootloader (HBBL)
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[https://git.raptorcs.com/git/talos-hostboot/tree/src/bootloader Source]
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| CPU core
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| SBE [[SEEPROM|SEEPROM]] (on CPU)
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|
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* first code which runs on main CPU cores; loads and executes rest of Hostboot
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* responsible for verifying integrity of Hostboot when secure boot is enabled, so this part of Hostboot is stored on the SBE SEEPROM, even though its source code lives inside the Hostboot repository
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|-
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| [[Hostboot|Hostboot]]
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[https://git.raptorcs.com/git/talos-hostboot/tree/ Raptor Source]
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[https://github.com/open-power/hostboot Upstream Source]
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| CPU core
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| [[PNOR|PNOR]] (SPI Flash)
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|
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* initialises DRAM (memory training, zeroing of ECC memory, etc.), processor bus, memory buffers
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* finally, chainloads Skiboot
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|-
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| [[Skiboot|Skiboot]]
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[https://git.raptorcs.com/git/talos-skiboot/tree/ Raptor Source]
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[https://github.com/open-power/skiboot Upstream Source]
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| CPU core
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| [[PNOR|PNOR]] (SPI Flash)
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|
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* initialises PCIe controllers, device trees, real time clock, NVlink, sensors
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* loads OCC firmware and starts OCC running
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* implements [[OpenPOWER Abstraction Layer|OpenPOWER Abstraction Layer]] (OPAL) for OS runtime services; remains resident in RAM after OS boot
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* finally, chainloads Skiroot
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|-
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| [[Skiroot]]/[[Petitboot|Petitboot]]
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[https://git.raptorcs.com/git/talos-op-build/tree/openpower/configs/linux/skiroot_defconfig Skiroot Linux Config Source (Talos II)]<br>
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[https://git.raptorcs.com/git/blackbird-op-build/tree/openpower/configs/linux/skiroot_defconfig Skiroot Linux Config Source (Blackbird)]<br>
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[https://git.raptorcs.com/git/talos-petitboot/ Petitboot Source]<br>
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[https://gitlab.raptorengineering.com/openpower-firmware/talos-op-build/-/blob/04-16-2019/openpower/configs/linux/skiroot_defconfig Skiroot Linux Config GitLab (Talos II)]<br>
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[https://gitlab.raptorengineering.com/openpower-firmware/blackbird-op-build/-/blob/04-16-2019/openpower/configs/linux/skiroot_defconfig Skiroot Linux Config GitLab (Blackbird)]
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| CPU core
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| [[PNOR|PNOR]] (SPI Flash)
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|
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* [[Skiroot]] refers to the Linux kernel and initramfs which runs from RAM
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* Contains [[Petitboot]], a userspace application which provides a boot menu
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* [[Petitboot]] loads operating system via kexec
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|-
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| OCC firmware
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[https://git.raptorcs.com/git/talos-occ/tree/ Raptor Source]
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[https://github.com/open-power/occ Upstream Source]
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| [[On-Chip Controller|OCC]] core (on CPU)
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| [[PNOR|PNOR]] (SPI Flash)
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| The [[On-Chip Controller|On-Chip Controller]] (OCC) manages:
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* thermal regulation of CPU chip, turbo frequency selection, voltage ID selection, power measurement, etc.
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|-
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| CME [[HCODE]]
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[https://git.raptorcs.com/git/talos-hcode/tree/ Raptor Source]
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[https://github.com/open-power/hcode Upstream Source]
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| [[CME]] cores (on CPU)
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| [[PNOR|PNOR]] (SPI Flash)
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| The [[Core Management Engine|Core Management Engines]] (CME) are auxillary cores used for power management purposes. They are ultimately responsible to the OCC.
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* There is one CME for every pair of SMT4 cores.
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|-
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| SGPE and PGPE [[HCODE]]
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[https://git.raptorcs.com/git/talos-hcode/tree/ Source]
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| [[SGPE]] and [[PGPE]] cores (on CPU)
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| [[PNOR|PNOR]] (SPI Flash)
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| [[GPE|General Purpose Engine]] (GPE) cores which assist, and are managed by, the OCC.
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* The [[SGPE|Stop GPEs]] (SGPEs) are part of the mechanism for resuming execution after a STOP instruction is executed (which is a Power ISA instruction which halts the processor).
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* The [[PGPE|Pstate GPEs]] (PGPEs) perform pstate management.
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|-
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| IOPPE [[HCODE]]
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[https://git.raptorcs.com/git/talos-hcode/tree/ Source]
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| [[IOPPE]] cores (on CPU)
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| [[PNOR|PNOR]] (SPI Flash)
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|
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* Involved in CAPI support.
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|- style="background-color:#e0e0e0;"
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| [[OpenBMC]]
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[https://git.raptorcs.com/git/talos-openbmc/tree/ Source]
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| BMC chip
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| BMC SPI Flash
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|
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<small>(This is not part of OpenPOWER firmware, but is mentioned to give a picture of the division of responsibilities. Not all POWER9 systems use a BMC; IBM systems use a [[FSP]].)</small>
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* Turns system power rails on and off to energise and deenergise CPU modules, RAM, etc.
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* Sends commands to CPU modules over [[FSI]] to commence booting.
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* Provides access to PNOR SPI flash containing host firmware via LPC.
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* Receives core temperature information from the [[OCC]]; decides and sets fan speeds.
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* Powers off system if [[OCC]] indicates catastrophic temperature.
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|}
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[[File:P9_ppe_instances.png|thumb|Diagram of main and auxillary cores on [[POWER9]]]]
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== Process ==
 +
 
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# [[OpenBMC|OpenBMC]] uses [[FSI|FSI]] interface to start SBE
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# SBE executes [[OTPROM|OTPROM]], which loads SEEPROM firmware into SBE PIBMEM
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# SBE executes SEEPROM firmware
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# [[Self-Boot Engine|SBE]] loads Hostboot 
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# [[Hostboot|Hostboot]] loads Skiboot
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# [[Skiboot|Skiboot]] loads [[OCC]], [[Skiroot]]
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# [[Petitboot|Petitboot]] application within [[Skiroot]] loads the operating system
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# OS talks to firmware through [[OpenPOWER Abstraction Layer|OPAL]]
  
 
== References ==
 
== References ==
  
 
<references/>
 
<references/>
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 +
== See also ==
 +
 +
* [[OpenBMC|OpenBMC]]
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* [[OpenPOWER|OpenPOWER]]
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* [[Talos_II/Firmware]]
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* [[Blackbird/Firmware]]
  
 
== External Links ==
 
== External Links ==
  
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* [https://github.com/open-power/docs OpenPOWER github account]
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* [https://github.com/open-power/docs OpenPOWER firmware source code on GitHub]
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* [https://github.com/open-power/docs OpenPOWER firmware documentation]
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* '''For a better understanding of OpenPOWER firmware and boot processes, see:'''
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** [https://github.com/open-power/docs/blob/master/hostboot/HostBoot_PG.md Overview of Boot Process]
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** [https://github.com/open-power/docs/blob/master/hostboot/P9_Boot_Flow_OpenPOWER.pdf P9 Boot Flow]
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** [https://github.com/open-power/docs More OpenPOWER firmware documentation]
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** [https://blog.jms.id.au/2015/07/openpower-firmware-stack/ OpenPOWER Firmware Stack] - Joel's Weblog
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* Bug tracker for firmware issues specific to [[Raptor Computing Systems|Raptor CS]] products: https://bugs.raptorengineering.com/
 
[[Category:Firmware]]
 
[[Category:Firmware]]

Latest revision as of 14:20, 3 March 2023

OpenPOWER Firmware is an open-source alternative to OpenFirmware and proprietary IBM firmware used on Power machines.[1] It is a general name for many separate pieces of software used to start recent Power Architecture chips made by IBM.[2]

OpenBMC is a separate project that creates firmware for the Baseboard Management Controller.

Components

Firmware Executed on Loaded from Function
SBE - OTPROM

Source

SBE core (on CPU) OTPROM (on CPU die) The portion of Self-Boot Engine (SBE) firmware permanently written via eFuses into the POWER9 silicon's OTPROM
  • very first instructions executed
  • loads remaining SBE firmware from SEEPROM into SBE core
SBE - SEEPROM

Source

SBE core (on CPU) SBE SEEPROM (on CPU) The portion of Self-Boot Engine (SBE) firmware run from rewritable SEEPROM
  • initialises CPU core
  • loads Hostboot Bootloader
  • backup copy stored on PNOR SPI Flash, used to stage SBE firmware updates
Hostboot Bootloader (HBBL)

Source

CPU core SBE SEEPROM (on CPU)
  • first code which runs on main CPU cores; loads and executes rest of Hostboot
  • responsible for verifying integrity of Hostboot when secure boot is enabled, so this part of Hostboot is stored on the SBE SEEPROM, even though its source code lives inside the Hostboot repository
Hostboot

Raptor Source Upstream Source

CPU core PNOR (SPI Flash)
  • initialises DRAM (memory training, zeroing of ECC memory, etc.), processor bus, memory buffers
  • finally, chainloads Skiboot
Skiboot

Raptor Source Upstream Source

CPU core PNOR (SPI Flash)
  • initialises PCIe controllers, device trees, real time clock, NVlink, sensors
  • loads OCC firmware and starts OCC running
  • implements OpenPOWER Abstraction Layer (OPAL) for OS runtime services; remains resident in RAM after OS boot
  • finally, chainloads Skiroot
Skiroot/Petitboot

Skiroot Linux Config Source (Talos II)
Skiroot Linux Config Source (Blackbird)
Petitboot Source
Skiroot Linux Config GitLab (Talos II)
Skiroot Linux Config GitLab (Blackbird)

CPU core PNOR (SPI Flash)
  • Skiroot refers to the Linux kernel and initramfs which runs from RAM
  • Contains Petitboot, a userspace application which provides a boot menu
  • Petitboot loads operating system via kexec
OCC firmware

Raptor Source Upstream Source

OCC core (on CPU) PNOR (SPI Flash) The On-Chip Controller (OCC) manages:
  • thermal regulation of CPU chip, turbo frequency selection, voltage ID selection, power measurement, etc.
CME HCODE

Raptor Source Upstream Source

CME cores (on CPU) PNOR (SPI Flash) The Core Management Engines (CME) are auxillary cores used for power management purposes. They are ultimately responsible to the OCC.
  • There is one CME for every pair of SMT4 cores.
SGPE and PGPE HCODE

Source

SGPE and PGPE cores (on CPU) PNOR (SPI Flash) General Purpose Engine (GPE) cores which assist, and are managed by, the OCC.
  • The Stop GPEs (SGPEs) are part of the mechanism for resuming execution after a STOP instruction is executed (which is a Power ISA instruction which halts the processor).
  • The Pstate GPEs (PGPEs) perform pstate management.
IOPPE HCODE

Source

IOPPE cores (on CPU) PNOR (SPI Flash)
  • Involved in CAPI support.
OpenBMC

Source

BMC chip BMC SPI Flash

(This is not part of OpenPOWER firmware, but is mentioned to give a picture of the division of responsibilities. Not all POWER9 systems use a BMC; IBM systems use a FSP.)

  • Turns system power rails on and off to energise and deenergise CPU modules, RAM, etc.
  • Sends commands to CPU modules over FSI to commence booting.
  • Provides access to PNOR SPI flash containing host firmware via LPC.
  • Receives core temperature information from the OCC; decides and sets fan speeds.
  • Powers off system if OCC indicates catastrophic temperature.
Diagram of main and auxillary cores on POWER9

Process

  1. OpenBMC uses FSI interface to start SBE
  2. SBE executes OTPROM, which loads SEEPROM firmware into SBE PIBMEM
  3. SBE executes SEEPROM firmware
  4. SBE loads Hostboot
  5. Hostboot loads Skiboot
  6. Skiboot loads OCC, Skiroot
  7. Petitboot application within Skiroot loads the operating system
  8. OS talks to firmware through OPAL

References

  1. ↑ Kerr, Jeremy. OpenPOWER: building an open-source software stack from bare metal. LCA 2015 - video on YouTube
  2. ↑ Smith, Stewart. Adventures in OpenPOWER Firmware. LCA 2016 - video on YouTube

See also

External Links

Retrieved from "https://wiki.raptorcs.com/w/index.php?title=OpenPOWER_Firmware&oldid=4199"