ThisIsAnEpicUsername wrote:
As far as I can see, the BIOS can be fully trusted with its allocations (unless its buggy, but thats unlikely, isn’t it? AHCI is pretty crucial to boot the OS, if its installed on a SATA drive).
It's actually very likely to be buggy. Firmware developers usually only check to make sure Windows can boot, so if Windows doesn't care that the firmware initialized something wrong, they won't bother to fix it.
ThisIsAnEpicUsername wrote:
What about command tables?
The firmware probably did set some of those up, but like everything else, you shouldn't rely on them.
ThisIsAnEpicUsername wrote:
When I allocate my command tables, do I need to set the memory region to uncached?
No. DMA is just a fancy name for when a device can read or write memory by itself instead of relying on the CPU to move data around.