PDBG

pdbg is a simple application to allow debugging of the host POWER processors from the BMC. It works in a similar way to JTAG programmers for embedded system development in that it allows you to access GPRs, SPRs and system memory.

A remote gdb sever is under development to allow integration with standard debugging tools.

Usage

The BMC must first be put into debug mode to allow access to the relevant GPIOs:

ipmitool -H <host> -U <username> -P <password> raw 0x3a 0x01

Usage is straight forward:

$ ./pdbg --help

Usage: ./pdbg [options] command ...

 Options:
        -c, --chip=chip
        -t, --thread=thread
        -h, --help

 Commands:
        getcfam <address>
        putcfam <address> <value>
        getscom <address>
        putscom <address> <value>
        getmem <address> <count>
        getgpr <gpr>
        getnia
        getspr <spr>
        stopchip
        startchip <threads>
        threadstatus

Probe chip and processor numbers

$ ./pdbg probe

Probing for valid processors...
        Processor-ID 0: 0x220ea04980000000
                Chiplet-ID 2 present
                Chiplet-ID 3 present
                Chiplet-ID 4 present
                Chiplet-ID 5 present
                Chiplet-ID 6 present
                Chiplet-ID 8 present
                Chiplet-ID 9 present
                Chiplet-ID 10 present
                Chiplet-ID 12 present
                Chiplet-ID 13 present
                Chiplet-ID 14 present
        Processor-ID 3: 0x220ea04982000000
                Chiplet-ID 1 present
                Chiplet-ID 2 present
                Chiplet-ID 5 present
                Chiplet-ID 6 present
                Chiplet-ID 9 present
                Chiplet-ID 10 present
                Chiplet-ID 11 present
                Chiplet-ID 12 present
                Chiplet-ID 13 present
                Chiplet-ID 14 present

Chiplet-IDs are core/chip numbers which should be passed as arguments to -c when performing operations such as getgpr that operate on particular cores. Processor-IDs should be passed as arguments to -p to operate on different processor chips.

Read SCOM register

$ ./pdbg getscom 0xf000f

0xf000f: 0x220ea04980000000

Write SCOM register on secondary processor

$ ./pdbg -p 3 putscom 0x8013c02 0x0

Read GPR on core/chip 2

$ ./pdbg -c 2 getgpr 2

r2 = 0xc00000000174fd00

Read SPR 8 (LR) on core/chip 2

$ ./pdbg -c 2 getspr 8

spr8 = 0xc000000000011824

Stop thread execution on core/chip 2

$ ./pdbg -c 2 stopchip

Previously active thread mask: 0x00
Thread 0 is STOPPED
Thread 1 is STOPPED
Thread 2 is STOPPED
Thread 3 is STOPPED
Thread 4 is STOPPED
Thread 5 is STOPPED
Thread 6 is STOPPED
Thread 7 is STOPPED

Get execution state on core/chip 2

$ ./pdbg -c 2 threadstatus

Thread 0 is STOPPED
Thread 1 is STOPPED
Thread 2 is STOPPED
Thread 3 is STOPPED
Thread 4 is STOPPED
Thread 5 is STOPPED
Thread 6 is STOPPED
Thread 7 is STOPPED

Restart thread execution on core/chip 2

The first parameter is the active thread mask returned when stopping the chip.

$ ./pdbg -c 2 startchip 0x00

Thread 0 is RUNNING
Thread 1 is RUNNING
Thread 2 is RUNNING
Thread 3 is RUNNING
Thread 4 is RUNNING
Thread 5 is RUNNING
Thread 6 is RUNNING
Thread 7 is RUNNING

madscientist159 / openbmc-firestone-pdbg