skiboot v5.9-rc1 was released on Wednesday October 11th 2017. It is the first release candidate of skiboot 5.9, which will become the new stable release of skiboot following the 5.8 release, first released August 31st 2017.

skiboot v5.9-rc1 contains all bug fixes as of skiboot-5.4.7 and skiboot-5.1.21 (the currently maintained stable releases). We do not currently expect to do any 5.8.x 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 5.9 by October 17th, with skiboot 5.9 being for all POWER8 and POWER9 platforms in op-build v1.20 (Due October 18th). This release will be targetted to early POWER9 systems.

Over skiboot-5.8, we have the following changes:

New Features


  • fast-reset by default (if possible)

    Currently, this is limited to POWER8 systems.

    A normal reboot will, rather than doing a full IPL, go through a fast reboot procedure. This reduces the “reboot to petitboot” time from minutes to a handful of seconds.


  • POWER9 power management during boot

    Less power should be consumed during boot.


    This implements OPAL_SIGNAL_SYSTEM_RESET, using scom registers to quiesce the target thread and raise a system reset exception on it. It has been tested on DD2 with stop0 ESL=0 and ESL=1 shallow power saving modes.

    DD1 is not implemented because it is sufficiently different as to make support difficult.

  • Enable deep idle states for POWER9

    • SLW: Add support for p9_stop_api

      p9_stop_api’s are used to set SPR state on a core wakeup form a deeper low power state. p9_stop_api uses low level platform formware and self-restore microcode to restore the sprs to requested values.

      Code is taken from :

    • SLW: Removing timebase related flags for stop4

      When a core enters stop4, it does not loose decrementer and time base. Hence removing flags OPAL_PM_DEC_STOP and OPAL_PM_TIMEBASE_STOP.

    • SLW: Allow deep states if homer address is known

      Use a common variable has_wakeup_engine instead of has_slw to tell if the: - SLW image is populated in case of power8 - CME image is populated in case of power9

      Currently we expect CME to be loaded if homer address is known ( except for simulators)

    • SLW: Configure self-restore for HRMOR

      Make a stop api call using libpore to restore HRMOR register. HRMOR needs to be cleared so that when thread exits stop, they arrives at linux system_reset vector (0x100).

    • SLW: Add opal_slw_set_reg support for power9

      This OPAL call is made from Linux to OPAL to configure values in various SPRs after wakeup from a deep idle state.

  • PHB4: CAPP recovery

    CAPP recovery is initiated when a CAPP Machine Check is detected. The capp recovery procedure is initiated via a Hypervisor Maintenance interrupt (HMI).

    CAPP Machine Check may arise from either an error that results in a PHB freeze or from an internal CAPP error with CAPP checkstop FIR action. An error that causes a PHB freeze will result in the link down signal being asserted. The system continues running and the CAPP and PSL will be re-initialized.

    This implements CAPP recovery for POWER9 systems

  • Add wafer-location property for POWER9

    Extract wafer-location from ECID and add property under xscom node. - bits 64:71 are the chip x location (7:0) - bits 72:79 are the chip y location (7:0)

    Sample output:

    [root@wsp xscom@623fc00000000]# lsprop ecid
    ecid             019a00d4 03100718 852c0000 00fd7911
    [root@wsp xscom@623fc00000000]# lsprop wafer-location
    wafer-location   00000085 0000002c
  • Add wafer-id property for POWER9

    Wafer id is derived from ECID data. - bits 4:63 are the wafer id ( ten 6 bit fields each containing a code)

    Sample output:

    [root@wsp xscom@623fc00000000]# lsprop ecid
    ecid             019a00d4 03100718 852c0000 00fd7911
    [root@wsp xscom@623fc00000000]# lsprop wafer-id
    wafer-id         "6Q0DG340SO"
  • Add ecid property under xscom node for POWER9. Sample output:

    [root@wsp xscom@623fc00000000]# lsprop ecid
    ecid             019a00d4 03100718 852c0000 00fd7911
  • Add ibm,firmware-versions device tree node

    In P8, hostboot provides mini device tree. It contains /ibm,firmware-versions node which has various firmware component version details.

    In P9, OPAL is building device tree. This patch adds support to parse VERSION section of PNOR and create /ibm,firmware-versions device tree node.

    Sample output:

    /sys/firmware/devicetree/base/ibm,firmware-versions # lsprop .
    occ              "6a00709"
    skiboot          "v5.7-rc1-p344fb62"
    buildroot        "2017.02.2-7-g23118ce"
    capp-ucode       "9c73e9f"
    petitboot        "v1.4.3-p98b6d83"
    sbe              "02021c6"
    open-power       "witherspoon-v1.17-128-gf1b53c7-dirty"


  • Disable Transactional Memory on Power9 DD 2.1

    Update pa_features_p9[] to disable TM (Transactional Memory). On DD 2.1 TM is not usable by Linux without other workarounds, so skiboot must disable it.

  • xscom: Do not print error message for ‘chiplet offline’ return values

    xscom_read/write operations returns CHIPLET_OFFLINE when chiplet is offline. Some multicast xscom_read/write requests from HBRT results in xscom operation on offline chiplet(s) and printing below warnings in OPAL console:

    [ 135.036327572,3] XSCOM: Read failed, ret = -14
    [ 135.092689829,3] XSCOM: Read failed, ret = -14

    Some SCOM users can deal correctly with this error code (notably opal-prd), so the error message is (in practice) erroneous.

  • IMC: Fix the core_imc_event_mask

    CORE_IMC_EVENT_MASK is a scom that contains bits to control event sampling for different machine state for core imc. The current event-mask setting sample events only on host kernel (hypervisor) and host userspace.

    Patch to enable the sampling of events in other machine states (like guest kernel and guest userspace).

  • IMC: Update the nest_pmus array with occ/gpe microcode uav updates

    OOC/gpe nest microcode maintains the list of individual nest units supported. Sync the recent updates to the UAV with nest_pmus array.

    For reference occ/gpr microcode link for the UAV:

  • Parse IOSLOT information from HDAT

    Add structure definitions that describe the physical PCIe topology of a system and parse them into the device-tree based PCIe slot description.

  • idle: user context state loss flags fix for stop states

    The “lite” stop variants with PSSCR[ESL]=PSSCR[EC]=1 do not lose user context, while the non-lite variants do (ESL: enable state loss).

    Some of the POWER9 idle states had these wrong.


  • POWER9 DD2 update

    The CAPI initialization sequence has been updated in DD2. This patch adapts to the changes, retaining compatibility with DD1. The patch includes some changes to DD1 fix-ups as well.

  • Load CAPP microcode for POWER9 DD2.0 and DD2.1

  • capi: Mask Psl Credit timeout error for POWER9

    Mask the PSL credit timeout error in CAPP FIR Mask register bit(46). As per the h/w team this error is now deprecated and shouldn’t cause any fir-action for P9.


A notabale change is that we now generate the device tree description of NVLINK based on the HDAT we get from hostboot. Since Hostboot will generate HDAT based on VPD, you now MUST have correct VPD programmed or we will default to a Sequoia layout, which will lead to random problems if you are not booting a Sequoia Witherspoon planar. In the case of booting with old VPD and/or Hostboot, we print a giant scary warning in order to scare you.

  • npu2: Read slot label from the HDAT link node

    Binding GPU to emulated NPU PCI devices is done using the slot labels since the NPU devices do not have a patching slot node we need to copy the label in here.

  • npu2: Copy link speed from the npu HDAT node

    This needs to be in the PCI device node so the speed of the NVLink can be passed to the GPU driver.

  • npu2: hw-procedures: Add settings to PHY_RESET

    Set a few new values in the PHY_RESET procedure, as specified by our updated programming guide documentation.

  • Parse NVLink information from HDAT

    Add the per-chip structures that descibe how the A-Bus/NVLink/OpenCAPI phy is configured. This generates the npu@xyz nodes for each chip on systems that support it.

  • npu2: Add vendor cap for IRQ testing

    Provide a way to test recoverable data link interrupts via a new vendor capability byte.

  • npu2: Enable recoverable data link (no-stall) interrupts

    Allow the NPU2 to trigger “recoverable data link” interrupts.

  • npu2: Implement basic FLR (Function Level Reset)

  • npu2: hw-procedures: Update PHY DC calibration procedure

  • npu2: hw-procedures: Change rx_pr_phase_step value


  • xive: Fix opal_xive_dump_tm() to access W2 properly. The HW only supported limited access sizes.

  • xive: Make opal_xive_allocate_irq() properly try all chips

    When requested via OPAL_XIVE_ANY_CHIP, we need to try all chips. We first try the current one (on which the caller sits) and if that fails, we iterate all chips until the allocation succeeds.

  • xive: Fix initialization & cleanup of HW thread contexts

    Instead of trying to “pull” everything and clear VT (which didn’t work and caused some FIRs to be set), instead just clear and then set the PTER thread enable bit. This has the side effect of completely resetting the corresponding thread context.

    This fixes the spurrious XIVE FIRs reported by PRD and fircheck

  • xive: Add debug option for detecting misrouted IPI in emulation

    This is high overhead so we don’t enable it by default even in debug builds, it’s also a bit messy, but it allowed me to detect and debug a locking issue earlier so it can be useful.

  • xive: Increase the interrupt “gap” on debug builds

    We normally allocate IPIs from 0x10. Make that 0x1000 on debug builds to limit the chances of overlapping with Linux interrupt numbers which makes debugging code that confuses them easier.

    Also add a warning in emulation if we get an interrupt in the queue whose number is below the gap.

  • xive: Fix locking around cache scrub & watch

    Thankfully the missing locking only affects debug code and init code that doesn’t run concurrently. Also adds a DEBUG option that checks the lock is properly held.

  • xive: Workaround HW issue with scrub facility

    Without this, we sometimes don’t observe from a CPU the values written to the ENDs or NVTs via the cache watch.

  • xive: Add exerciser for cache watch/scrub facility in DEBUG builds

  • xive: Make assertion in xive_eq_for_target() more informative

  • xive: Add debug code to check initial cache updates

  • xive: Ensure pressure relief interrupts are disabled

    We don’t use them and we hijack the VP field with their configuration to store the EQ reference, so make sure the kernel or guest can’t turn them back on by doing MMIO writes to ACK#

  • xive: Don’t try setting the reserved ACK# field in VPs

    That doesn’t work, the HW doesn’t implement it in the cache watch facility anyway.

  • xive: Remove useless memory barriers in VP/EQ inits

    We no longer update “live” memory structures, we use a temporary copy on the stack and update the actual memory structure using the cache watch, so those barriers are pointless.


  • phb4: Mask RXE_ARB: DEC Stage Valid Error

    Change the inits to mask out the RXE ARB: DEC Stage Valid Error (bit 370. This has been a fatal error but should be informational only.

    This update will be in the next version of the phb4 workbook.

  • phb4: Add additional adapter to retrain whitelist

    The single port version of the ConnectX-5 has a different device ID 0x1017. Updated descriptions to match pciutils database.

  • PHB4: Default to PCIe GEN3 on POWER9 DD2.00

    You can use the NVRAM override for DD2.00 screened parts.

  • phb4: Retrain link if degraded

    On P9 Scale Out (Nimbus) DD2.0 and Scale in (Cumulus) DD1.0 (and below) the PCIe PHY can lockup causing training issues. This can cause a degradation in speed or width in ~5% of training cases (depending on the card). This is fixed in later chip revisions. This issue can also cause PCIe links to not train at all, but this case is already handled.

    This patch checks if the PCIe link has trained optimally and if not, does a full PHB reset (to fix the PHY lockup) and retrain.

    One complication is some devices are known to train degraded unless device specific configuration is performed. Because of this, we only retrain when the device is in a whitelist. All devices in the current whitelist have been testing on a P9DSU/Boston, ZZ and Witherspoon.

    We always gather information on the link and print it in the logs even if the card is not in the whitelist.

    For testing purposes, there’s an nvram to retry all PCIe cards and all P9 chips when a degraded link is detected. The new option is ‘pci-retry-all=true’ which can be set using: nvram -p ibm,skiboot –update-config pci-retry-all=true. This option may increase the boot time if used on a badly behaving card.

IBM FSP platforms

  • FSP/NVRAM: Handle “get vNVRAM statistics” command

    FSP sends MBOX command (cmd : 0xEB, subcmd : 0x05, mod : 0x00) to get vNVRAM statistics. OPAL doesn’t maintain any such statistics. Hence return FSP_STATUS_INVALID_SUBCMD.

    Fixes these messages appearing in the OPAL log:

    [16944.384670488,3] FSP: Unhandled message eb0500
    [16944.474110465,3] FSP: Unhandled message eb0500
    [16945.111280784,3] FSP: Unhandled message eb0500
    [16945.293393485,3] FSP: Unhandled message eb0500
  • fsp: Move common prints to trace

    These two prints just end up filling the skiboot logs on any machine that’s been booted for more than a few hours.

    They have never been useful, so make them trace level. They were: ::

    SURV: Received heartbeat acknowledge from FSP SURV: Sending the heartbeat command to FSP

BMC based systems

  • hw/lpc-uart: read from RBR to clear character timeout interrupts

    When using the aspeed SUART, we see a condition where the UART sends continuous character timeout interrupts. This change adds a (heavily commented) dummy read from the RBR to clear the interrupt condition on init.

    This was observed on p9dsu systems, but likely applies to other systems using the SUART.

  • astbmc: Add methods for handing Device Tree based slots e.g. ones from HDAT on POWER9.


  • ipmi: Convert common debug prints to trace

    OPAL logs messages for every IPMI request from host. Sometime OPAL console is filled with only these messages. This path is pretty stable now and we have enough logs to cover bad path. Hence lets convert these debug message to trace/info message. Examples are:

    [ 1356.423958816,7] opal_ipmi_recv(cmd: 0xf0 netfn: 0x3b resp_size: 0x02)
    [ 1356.430774496,7] opal_ipmi_send(cmd: 0xf0 netfn: 0x3a len: 0x3b)
    [ 1356.430797392,7] BT: seq 0x20 netfn 0x3a cmd 0xf0: Message sent to host
    [ 1356.431668496,7] BT: seq 0x20 netfn 0x3a cmd 0xf0: IPMI MSG done
  • libflash/file: Handle short read()s and write()s correctly

    Currently we don’t move the buffer along for a short read() or write() and nor do we request only the remaining amount.

  • hw/p8-i2c: Rework timeout handling

    Currently we treat a timeout as a hard failure and will automatically fail any transations that hit their timeout. This results in unnecessarily failing I2C requests if interrupts are dropped, etc. Although these are bad things that we should log we can handle them better by checking the actual hardware status and completing the transation if there are no real errors. This patch reworks the timeout handling to check the status and continue the transaction if it can. if it can while logging an error if it detects a timeout due to a dropped interrupt.

  • core/flash: Only expect ELF header for BOOTKERNEL partition flash resource

    When loading a flash resource which isn’t signed (secure and trusted boot) and which doesn’t have a subpartition, we assume it’s the BOOTKERNEL since previously this was the only such resource. Thus we also assumed it had an ELF header which we parsed to get the size of the partition rather than trusting the actual_size field in the FFS header. A previous commit (9727fe3 DT: Add ibm,firmware-versions node) added the version resource which isn’t signed and also doesn’t have a subpartition, thus we expect it to have an ELF header. It doesn’t so we print the error message “FLASH: Invalid ELF header part VERSION”.

    It is a fluke that this works currently since we load the secure boot header unconditionally and this happen to be the same size as the version partition. We also don’t update the return code on error so happen to return OPAL_SUCCESS.

    To make this explicitly correct; only check for an ELF header if we are loading the BOOTKERNEL resource, otherwise use the partition size from the FFS header. Also set the return code on error so we don’t erroneously return OPAL_SUCCESS. Add a check that the resource will fit in the supplied buffer to prevent buffer overrun.

  • flash: Support adding the no-erase property to flash

    The mbox protocol explicitly states that an erase is not required before a write. This means that issuing an erase from userspace, through the mtd device, and back returns a successful operation that does nothing. Unfortunately, this makes userspace tools unhappy. Linux MTD devices support the MTD_NO_ERASE flag which conveys that writes do not require erases on the underlying flash devices. We should set this property on all of our devices which do not require erases to be performed.

    NOTE: This still requires a linux kernel component to set the MTD_NO_ERASE flag from the device tree property.


  • external/gard: Clear entire guard partition instead of entry by entry

    When using the current implementation of the gard tool to ecc clear the entire GUARD partition it is done one gard record at a time. While this may be ok when accessing the actual flash this is very slow when done from the host over the mbox protocol (on the order of 4 minutes) because the bmc side is required to do many read, erase, writes under the hood.

    Fix this by rewriting the gard tool reset_partition() function. Now we allocate all the erased guard entries and (if required) apply ecc to the entire buffer. Then we can do one big erase and write of the entire partition. This reduces the time to clear the guard partition to on the order of 4 seconds.

  • opal-prd: Fix opal-prd command line options

    HBRT OCC reset interface depends on service processor type.

    • FSP: reset_pm_complex()

    • BMC: process_occ_reset()

    We have both occ and pm-complex command line interfaces. This patch adds support to dispaly appropriate message depending on system type.





    opal-prd occ

    display error message


    opal-prd pm-complex

    Call pm_complex_reset()


    opal-prd occ

    Call process_occ_reset()


    opal-prd pm-complex

    display error message

  • opal-prd: detect service processor type and then make appropriate occ reset call.

  • pflash: Fix erase command for unaligned start address

    The erase_range() function handles erasing the flash for a given start address and length, and can handle an unaligned start address and length. However in the unaligned start address case we are incorrectly calculating the remaining size which can lead to incomplete erases.

    If we’re going to update the remaining size based on what the start address was then we probably want to do that before we overide the origin start address. So rearrange the code so that this is indeed the case.

  • external/gard: Print an error if run on an FSP system


  • mambo: Add mambo socket program

    This adds a program that can be run inside a mambo simulator in linux userspace which enables TCP sockets to be proxied in and out of the simulator to the host.

    Unlike mambo bogusnet, it’s requires no linux or skiboot specific drivers/infrastructure to run.

    Run inside the simulator:

    • to forward host ssh connections to sim ssh server: ./mambo-socket-proxy -h 10022 -s 22, then connect to port 10022 on your host with ssh -p 10022 localhost

    • to allow http proxy access from inside the sim to local http proxy: ./mambo-socket-proxy -b proxy.mynetwork -h 3128 -s 3128

    Multiple connections are supported.

  • idle: disable stop*_lite POWER9 idle states for Mambo platform

    Mambo prior to Mambo.7.8.21 had a bug where the stop idle instruction with PSSCR[ESL]=PSSCR[EC]=0 would resume with MSR set as though it had taken a system reset interrupt.

    Linux currently executes this instruction with MSR already set that way, so the problem went unnoticed. A proposed patch to Linux changes that, and causes the idle code to crash. Work around this by disabling lite stop states for the mambo platform for now.