Hostboot kernel log

On an OpenPower system, the hostboot kernel can be fetched from the host using pdbg to read host memory.

You will need a copy of the symbols contained in hbicore in order to find the address of kernel_printk_buffer. If you’ve built locally, that could be found in hostboot/img/hibcore.elf:

$ nm hostboot/img/hbicore.elf | grep kernel_printk_buffer
0000000000040278 D kernel_printk_buffer

If you’ve grabbed a test build from eg., download the corresponding host_fw_debug.tar, and extract it in a directory as follows:

$ tar xf ~/Downloads/host_fw_debug.tar hbicore.syms
$ grep kernel_printk_buffer  hbicore.syms

We now have the offset from the hostboot base address: 0x00040278.

Hostboot runs at 0x8000000, so the address of interest for this build is 0x80040278. (FWIW, this address appears to be fixed between a bunch of hostboot builds that I’ve looked at).

On your BMC:

$ pdbg -p 0 getmem 0x8040278 500 > /tmp/hb-log
$ cat /tmp/hb-log
Booting Hostboot kernel...
CPU=Nimbus  PIR=0
Valid BlToHbData found at 0x80E2000
lpc=6030000000000, xscom=603FC00000000
iv_lpc=6030000000000, iv_xscom=603FC00000000, iv_data=0x454a8
HRMOR = 8000000
Hostboot base image ends at 0x98000...
PageManager end of preserved area at 0XE7000
PageManager page table offset at 0X100000
729 pages.
Starting init!
Bringing up VFS...done.
Initializing modules.
        Initing module
        Initing module
        Initing module
        Initing module
        Initing module
        Initing module
        Initing module
        Initing module
        Initing module
        Initing module
        Initing module
Modules initialized.
init_main: Starting Initialization Service...
InitService entry.
Addr [0], magic[50415254] checksum[0]
forced to true - l_isActiveTOC=1
SECUREBOOT::enabled() state:0
ExtInitSvc entry.
ast2400: SUART config in process
UART: Device initialized.
IStepDispatcher entry.
Set MchChk Xstop: 0x800603fc05012000=0000000100000000
Winkle threads - 0123.... - Awake!
Written on June 6, 2018