I'm pretty late to this, but the navi firmware didn't work on previous firmware versions since it was too big to fit on bootkernfw. I swapped my rx5300 out for an rx560 and loaded the polaris fw to bootkernfw, and it worked perfectly fine for me- I get a picture in petitboot, and I boot to desktop in fedora without any issues. Not sure if it's something with navi cards, or just mine in particular (I don't have any other ones I could test it with). Guess I'll just stick with the rx560 for now.
Well BOOTKERNFW partition was intended to workaround the ever-growing kernel image size, it's interesting that you say it would not be able to fit the firmware. Btw I highly recommend you try to build the upstream open-power firmware version (please see my branch
https://github.com/runlevel5/op-build/tree/amdgpu-navi23 and adapt to whatever amdgpu firmware blob you prefer and compile the firmware from scratch). Please notes there has been discrepancies between Raptor's downstream and open-power upstream version. The first major change is that upstream version does NOT use BOOTKERNFW (that means maintainers have to adjust size offset to make everything within size budget). Other changes are:
### Firmware components
| Component | open-power upstream | Raptor (Raptor GitLab fork) |
|---|---|---|
| hostboot | `6b6646f0` (2026-03-10) | `a98d7347` (2024-02-15 era) |
| skiboot | `v7.1-131-g9abbfe67df5b` | `ecb1dc7c` |
| hcode | `hw091323a.opmst` | `9b705d0e` |
| sbe | `e66523bb` | `f5dcee93` |
| occ | `3515ab0e` | `9ddc6ba5` |
| petitboot | 1.15 (release tarball) | `695b1d97` (git pin from fork) |
| machine-xml | (per-platform tree) | `e782e308` (Blackbird) / `cbd11e94` (Talos II) |
| libflash | follows skiboot | `ecb1dc7c` (same as skiboot fork) |
| openpower-ffs | `3ec70fbc` | `3ec70fbc` (**identical**) |
| openpower-pnor | `3e9fa97d` (open-power/pnor) | `92c0451c` (**Raptor's pnor fork**) |
| ima-catalog | `89e00ee3` | `3d30c7ac` |
| ppe42-gcc | `b4772a9f` | `84a6a88e` |
| ppe42-binutils | `c615a89c` | `2552229791` |
| capp-ucode | `p9-dd2-v4` | `p9-dd2-v4` (same tag, separately hosted) |
| pnv-lpc | not pinned | `90e170ca` |
| ocmb-explorer-fw | 4.0 | **REMOVED** |
### Linux kernel
| | Ours | Raptor |
|---|---|---|
| Version | 6.12.87 | v6.6.16 |
| Source | `kernel.org/.../linux-6.12.87.tar.xz` | `gitlab.raptorengineering.com/openpower-firmware/talos-op-linux` (Blackbird) or `.../common-cpu-ibm-power9/op-linux` (Talos II) — **custom fork** |
| In-tree patches | 2 (xhci, EXTRAVERSION) | 6 (xhci, EXTRAVERSION, AST palette, AST RAMDAC reset, AST DVO enable, powerpc gpr1/fpu) |
| Skiroot defconfig location | `openpower/configs/linux/skiroot_defconfig` | same |
And other patches that Raptor introduced to various components.
In summary, just give upstream a try to see if it works for you, if it does, we could propose to Raptor to find a solution for limited size of BOOTKERNFW.
P/S: It would be great if Raptor could rebase their downstream fork with upstream - lots of components are so out of date