phbl

One can trade run-time flexibility for size, speed, and small attack surface. Taken to the limit, Oxide Computer boots using the [Pico Host Boot Loader](https://github.com/oxidecomputer/phbl) which is probably not suitable for your personal system where you would want to boot many OS images from many devices on many different mainboards using very similar or modular boot flash images. Phbl transfers control to a partial Unix image, also in the boot flash, which brings in the rest of the OS from a well-known boot device. There is no UEFI, CoreBoot, PXE boot etc. The AMD PSP code does run, but that's the only early external blob in the boot path. This does mean that the OS has to understand its hardware, there is minimal "free" initialization.

So, your comment was not dead when I saw it. This reply was, but apparently now has been vouched for. > What happened to Project X (supposedly coreboot++ for latest AMD CPUs)? I don't recall what you're referring to specifically, maybe this was a thing before I started at Oxide. I do know that we deliberately decided to not go with coreboot. I believe the equivalent component would be phbl[1]. It boots illumos directly. Bryan gave a talk about how we boot[1][2] with more reasoning and context. > Does Oxide attempt to sandbox, completely remove or 'verify as benign' aspects like the PSP? The general attitude is still "remove or work around every binary blob possible," but the PSP is unfortunately not able to be worked around. > However, if the hardware platform is FOSS We fully intend to do this, by the way. Just haven't yet. It'll come. 1

Oxide managed to do something similar as well: https://github.com/oxidecomputer/phbl

They have a custom bootloader https://github.com/oxidecomputer/phbl that runs without AGESA or any of the normal stack of stuff. From their podcast it sounds like it was quite a bit of work to get it working.

(The AGESA bootloader -- or ABL -- is in the AMD PSP.) In terms of our replacement for AGESA: the PSP boots to our first instruction, which is the pico host bootloader, phbl[0]. phbl then loads the actual operating system[1], which performs platform enablement as part of booting. (This is pretty involved, but to give you a flavor, see, e.g. initialization of the DXIO engine.[2]) [0] https://github.com/oxidecomputer/phbl [1] https://github.com/oxidecomputer/illumos-gate/tree/stlouis [2] https://github.com/oxidecomputer/illumos-gate/blob/stlouis/u...

Oxide phbl https://github.com/oxidecomputer/phbl doesn't use OpenSIL. I assume it's written from scratch based on documentation and maybe looking at AGESA. Why can't other server/firmware vendors do the same? Because they're just not willing to.