skiboot-5.5.0-rc2 was released on Monday April 3rd 2017. It is the second release candidate of skiboot 5.5, which will become the new stable release of skiboot following the 5.4 release, first released November 11th 2016.

skiboot-5.5.0-rc2 contains all bug fixes as of skiboot-5.4.3 and skiboot-5.1.19 (the currently maintained stable releases).

For how the skiboot stable releases work, see Skiboot stable tree rules and releases for details.

The current plan is to cut the final 5.5.0 by April 8th, with skiboot 5.5.0 being for all POWER8 and POWER9 platforms in op-build v1.16 (Due April 12th). This is a short cycle as this release is mainly targetted towards POWER9 bringup efforts.

Following skiboot-5.5.0, we will move to a regular six week release cycle, similar to op-build, but slightly offset to allow for a short stabilisation period. Expected release dates and contents are tracked using GitHub milestone and issues:

Over skiboot-5.5.0-rc1, we have the following changes:


  • Introduce NPU2 support

    NVLink2 is a new feature introduced on POWER9 systems. It is an evolution of of the NVLink1 feature included in POWER8+ systems but adds several new features including support for GPU address translation using the Nest MMU and cache coherence.

    Similar to NVLink1 the functionality is exposed to the OS as a series of virtual PCIe devices. However the actual hardware interfaces are significantly different which limits the amount of common code that can be shared between implementations in the firmware.

    This patch adds basic hardware initialisation and exposure of the virtual NVLink2 PCIe devices to the running OS.

  • npu2: Add OPAL calls for nvlink2 address translation services (see OPAL NPU2 calls)

    Adds three OPAL calls for interacting with NPU2 devices: OPAL_NPU_INIT_CONTEXT, OPAL_NPU_DESTROY_CONTEXT and OPAL_NPU_MAP_LPAR.

    These are used to setup and configure address translation services (ATS) for a process/partition on a given NVLink2 device.


  • hdata/memory: ignore homer and occ reserved ranges

    We populate these from the HOMER BARs in the PBA directly. There’s no need to take the hostboot supplied values so just ignore the corresponding reserved ranges.

  • hdata/vpd: Parse the OpenPOWER OPFR record

    Parse the OpenPOWER FRU VPD (OPFR) record on OpenPOWER instead of the VINI records.

  • hdata/vpd: Parse additional VINI records

    These records provide hardware version details, CCIN extension information, card type details and hardware characteristics of the FRU

  • hdata/cpu: account for p9 shared caches

    On P9 the L2 and L3 caches are shared between pairs of SMT=4 cores. Currently this is not accounted for when creating caches nodes in the device tree. This patch adds additional checking so that a cache node is only created for the first core in the pair and the second core will reference the cache correctly.

  • hdata: print backtraces on HDAT errors

  • hdat: ignore zero length reserves

    Hostboot can export reserved regions with a length of zero and these should be ignored rather than being turned into reserved range. While we’re here fix a memory leak by moving the “too large” region check to before we allocate space for the label.

  • SLW: Add init for power9 power management

    This patch adds new function to init core for power9 power management. SPECIAL_WKUP_* SCOM registers, if set, can hold the cores from going into idle states. Hence, clear PPM_SPECIAL_WKUP_HYP_REG scom register for each core during init. (This init are not required for MAMBO)


  • hw/phb3: Adjust ECRC on root port dynamically

    The Samsung NVMe adapter is lost when it’s connected to PMC 8546 PCIe switch, until ECRC is disabled on the root port. We found similar issue prevously when Broadcom adapter is connected to same part of PCIe switch and it was fixed by commit 60ce59ccd0e9 (“hw/phb3: Disable ECRC on Broadcom adapter behind PMC switch”). Unfortunately, the commit doesn’t fix the Samsung NVMe adapter lost issue.

    This fixes the issues by disable ECRC generation/check on root port when PMC 8546 PCIe switch ports are found. This can be extended for other PCIe switches or endpoints in future: Each PHB maintains the count of PCI devices (PMC 8546 PCIe switch ports currently) which require to disable ECRC on root port. The ECRC functionality is enabled when first PMC 8546 switch port is probed and disabled when last PMC 8546 switch port is destroyed (in PCI hot remove scenario). Except PHB’s reinitialization after complete reset, the ECRC on root port is untouched.

  • core/pci: Fix lost NVMe adapter behind PMC 8546 switch

    The NVMe adapter in below PCI topology is lost. The root cause is the presence bit on its PCI slot is missed, but the PCIe link has been up. The PCI core doesn’t probe the adapter behind the slot, leading to lost NVMe adapter in the particular case.

    • PHB3 root port

    • PLX switch 8748 (10b5:8748)

    • PLX swich 9733 (10b5:9733)

    • PMC 8546 swtich (11f8:8546)

    • NVMe adapter (1c58:0023)

    This fixes the issue by overriding the PCI slot presence bit with PCIe link state bit.

  • hw/phb4: Locate AER capability position if necessary

  • core/pci: Disable surprise hotplug on root port

  • core/pci: Ignore PCI slot capability on root port

    We are creating PCI slot on root port, where the PCI slot isn’t supported from hardware. For this case, we shouldn’t read the PCI slot capability from hardware. When bogus data returned from the hardware, we will attempt to the PCI slot’s power state or enable surprise hotplug functionality. All of them can’t be accomplished without hardware support.

    This leaves the PCI slot’s capability list 0 if PCICAP_EXP_CAP_SLOT isn’t set in hardware (pcie_cap + 0x2). Otherwise, the PCI slot’s capability list is retrieved from hardware (pcie_cap + 0x14).

  • phb4: Default to PCIe GEN2 on DD1

    Default to PCIe GEN2 link speeds on DD1 for stability.

    Can be overridden using nvram pcie-max-link-speed=4 parameter.

  • phb3/4: Set max link speed via nvram

    This adds an nvram parameter pcie-max-link-speed to configure the max speed of the pcie link. This can be set from the petitboot prompt using:

    nvram -p ibm,skiboot --update-config pcie-max-link-speed=4

    This takes preference over anything set in the device tree and is global to all PHBs.


  • Mambo/Qemu boot tests: expect (and fail) on checkstop

    This allows us to fail a lot faster if we checkstop