> >> Generally, I wouldn't assume / want board-specific drivers outside of > >> coreboot. It seems board-specific table entries would invite people to > >> write such > >> > > > > I don't think this is encouraging board-specific drivers; just trying to > > pass information to the payload here, that's all. > > Wouldn't that payload then naturally contain a board-specific driver? I > mean is it just displaying or storing the information or is it acting on > it?
Yes, payloads contain board-specific drivers. Isn't that how it's always been? We have always had a split of responsibility between coreboot and the payload -- for example, USB, storage devices, audio devices, etc. have always only been initialized in the payload and coreboot generally doesn't know anything about them. How else is the payload supposed to do that other than hardcoding board-specific knowledge? On Arm platforms generally none of these devices are enumerable, so the payload needs to know what address to find the eMMC controller at, needs to have a driver to talk to it and needs to know the maximum speed supported by the eMMC part on that board. We do all of this by hardcoding board-specific information, and occasionally (e.g. when multi-sourcing eMMC parts on what's otherwise the same board) it is convenient to support multiple board SKUs in the same image by looking up this information in a table indexed by a strapping ID. When the device this information belongs to is wholly controlled and initialized by the payload and coreboot doesn't know anything about it, I think it makes sense for that table to also be in the payload. (Note that on Arm devices we take this even further, and those strapping IDs are also used to look up the right kernel device tree to make sure the kernel can have the right information about those strapping-dependent devices. It's board-specific information all the way down.) We've been using this set of strapping IDs for many years, Tim's patch is just more efficiently organizing a set of existing concepts that had been slowly added piece by piece over time. I hope it shouldn't be too controversial. _______________________________________________ coreboot mailing list -- [email protected] To unsubscribe send an email to [email protected]
