Add GPU Firmware To BOOTKERNFW

Purpose

This guide explains how to add GPU (or other) firmware files to the BOOTKERNFW partition of the boot firmware flash. This allows Linux kernel drivers which require firmware blobs to function correctly within the Skiroot bootloader environment.

For example, the amdgpu driver requires AMD firmware blobs to bring up AMD GPUs. Copying these files into the firmware partition enables attached displays to be brought up when showing the boot menu.

Background

Many cards require firmware to be loaded at startup time to initialize. On an X86 system, this is usually accomplished by bootstrap code called an "Option ROM", or by extra code in the BIOS.

On POWER, this is not a possibility, due to the Option ROM code being platform-specific, as well as the POWER security stance being that trusting random bootstrap code on cards is a bad idea.

Therefore, for things like video cards to work, it is necessary for the card's firmware to be loaded in before the card can be used. Linux video drivers in petitboot are capable of doing this loading, however, the actual firmware itself needs to be available so the drivers actually have something to load.

So, on RCS OpenPOWER systems, there is a special area of flash set aside for user-provided firmware files, called BOOTKERNFW. Due to the limited size of this partition, the user is required to make decisions as to what firmware files to install.

Applicability

All RCS OpenPOWER systems.

Instructions

Step 1. Generate firmware partition image

Boot into an OS. A Linux environment is assumed. You will need the mksquashfs tool available.

For Debian, you can install mksquashfs using the following command:

$ apt install squashfs-tools

Create a directory with the required firmware files available:

$ mkdir /tmp/firmware
$ # ... (copy required files into /tmp/firmware) ...

The directory structure under /tmp/firmware gets mounted at /lib/firmware. Here is an example of the required directory structure:

/tmp/firmware/radeon/PITCAIRN_pfp.bin
/tmp/firmware/amdgpu/polaris10_mc.bin

You can obtain these firmware files from most Linux distros (they tend to be installed in /lib/firmware), or from the linux-firmware repository.

Having generated the correct directory structure, generate the image:

$ cd /tmp/firmware
$ mksquashfs * /tmp/firmware.bin -all-root -keep-as-directory

firmware.bin is now a SquashFS image which you will copy to a firmware flash partition. You will need to access this image while in the Skiroot environment, so you may wish to copy it to e.g. /boot or another partition which you can easily access from Skiroot.

Step 2. Copy firmware partition image to flash

Reboot into the Skiroot environment, attaching a display using the onboard VGA or HDMI port if necessary. When the Petitboot bootloader appears, select “Exit to Shell”.

Make sure you can see the BOOTKERNFW partition (should return: mtd5: 000e0000 00010000 "BOOTKERNFW"):

# cat /proc/mtd | grep BOOTKERNFW

Find the flash_erase (mine was in /var/petitboot/mnt/dev/nvme0n1p2/usr/sbin/):

# find / -name flash_erase

Erase /dev/mtd5:

# /var/petitboot/mnt/dev/nvme0n1p2/usr/sbin/flash_erase /dev/mtd5 0 0

Flash /dev/mtd5:

# dd if=/var/petitboot/mnt/dev/nvme0n1p2/boot/firmware.bin of=/dev/mtd5 bs=64k

Reboot the system:

# reboot

When the system reboots, exit into the shell at the Petitboot menu again and check to see if the firmware made it as expected:

# ls /lib/firmware/

Notes

If you are still getting an error message about not being able to find VGA BIOS, it may be because your GPU is being initialized before /lib/firmware is mounted. You can check this by running dmesg from the Skiroot shell. For example, my GPU was trying to initialize at around T+6.5 seconds and the mtd device wasn't actually mounted until T+7.25. I was able to successfully load the firmware after after /dev/mtd5 was mounted by running rmmod amdgpu && modprobe amdgpu from the shell. However, I did experience stability issues in Debian Stretch with amdgpu. However, if I let Skiroot fail to load the firmware and boot anyway, the radeon driver works fine.

e.g.

$ dmesg
...
[    6.412518] [drm] radeon kernel modesetting enabled.
[    6.412848] pci 0033:00:00.0: enabling device (0105 -> 0107)
[    6.412867] radeon 0033:01:00.0: enabling device (0140 -> 0142)
[    6.413077] [drm] initializing kernel modesetting (PITCAIRN 0x1002:0x6819 0x1043:0x0431 0x00).
[    6.413086] radeon: No suitable DMA available
[    6.413150] [drm:radeon_device_init] *ERROR* Unable to find PCI I/O BAR
[    6.533321] [drm:radeon_atombios_init] *ERROR* Unable to find PCI I/O BAR; using MMIO for ATOM IIO
[    6.533415] ATOM BIOS: 6819.15.17.0.0.AS01
[    6.533434] [drm] GPU not posted. posting now...
[    6.541203] radeon 0033:01:00.0: VRAM: 2048M 0x0000000000000000 - 0x000000007FFFFFFF (2048M used)
[    6.541208] radeon 0033:01:00.0: GTT: 2048M 0x0000000080000000 - 0x00000000FFFFFFFF
[    6.541211] [drm] Detected VRAM RAM=2048M, BAR=256M
[    6.541213] [drm] RAM width 256bits DDR
[    6.541295] [TTM] Zone  kernel: Available graphics memory: 50118240 kiB
[    6.541297] [TTM] Zone   dma32: Available graphics memory: 2097152 kiB
[    6.541299] [TTM] Initializing pool allocator
[    6.541371] [drm] radeon: 2048M of VRAM memory ready
[    6.541374] [drm] radeon: 2048M of GTT memory ready.
[    6.541390] [drm] Loading pitcairn Microcode
[    6.541429] radeon 0033:01:00.0: Direct firmware load for radeon/pitcairn_pfp.bin failed with error -2
[    6.541456] radeon 0033:01:00.0: Direct firmware load for radeon/PITCAIRN_pfp.bin failed with error -2
[    6.541459] si_cp: Failed to load firmware "radeon/PITCAIRN_pfp.bin"
[    6.541560] [drm:si_init] *ERROR* Failed to load firmware!
[    6.541653] radeon 0033:01:00.0: Fatal error during GPU init
[    6.541772] [drm] radeon: finishing device.
...
[    7.123614] 6 ofpart partitions found on MTD device flash
[    7.123617] Creating 6 MTD partitions on "flash":
[    7.123621] 0x000000000000-0x000004000000 : "PNOR"
[    7.123773] 0x000001b21000-0x000003a21000 : "BOOTKERNEL"
[    7.123868] 0x000003b44000-0x000003b68000 : "CAPP"
[    7.123961] 0x000003b88000-0x000003b89000 : "VERSION"
[    7.124056] 0x000003b89000-0x000003bc9000 : "IMA_CATALOG"
[    7.124149] 0x000003f10000-0x000003ff0000 : "BOOTKERNFW"
...
$ rmmod amdgpu && modprobe amdgpu
$ dmesg
...
[ 2727.836343] [drm] amdgpu kernel modesetting enabled.
[ 2727.836900] amdgpu 0033:01:00.0: SI support provided by radeon.
[ 2727.836905] amdgpu 0033:01:00.0: Use radeon.si_support=0 amdgpu.si_support=1 to override.