On Mon, Jan 30, 2023 at 03:24:40PM +0000, Matthew Wilcox wrote: > > Basically we are making use of the memory protection unit (MPU) so > > that only M-mode is allowed to access this region and S/U modes are > > blocked. > > This sounds like RISC-V terminology. I have no idea what M, S or U > modes are (Supervisor and User, I'd guess for the last two?) Yes, M = Machine, S = Supervisor, and U = User. M omde is the absolutele worst idea of RISC-V and basically a mix of microcode and super-SMM mode. > Before we go too deeply into it, how much would it cost to buy all of > these parts and feed them into a shredder? I'm not entirely joking; > if it's less than the software engineering time it'd take to develop > and support this feature, we should do it. The above suggests this is in no way an actual hardware problem, but the stupid decision is done in the M-Mode firmware. I think it is very reasonable to simply not support the devices in Linux until the firmware is fixed.
