On Fri, Jan 29, 2021 at 04:24:33PM -0800, Ben Widawsky wrote: > The CXL memory device send interface will have a number of supported > commands. The raw command is not such a command. Raw commands allow > userspace to send a specified opcode to the underlying hardware and > bypass all driver checks on the command. This is useful for a couple of > usecases, mainly: > 1. Undocumented vendor specific hardware commands > 2. Prototyping new hardware commands not yet supported by the driver This sounds like a recipe for .. In case you really really want this may I recommend you do two things: - Wrap this whole thing with #ifdef CONFIG_CXL_DEBUG_THIS_WILL_DESTROY_YOUR_LIFE (or something equivalant to make it clear this should never be enabled in production kernels). - Add a nice big fat printk in dmesg telling the user that they are creating a unstable parallel universe that will lead to their blood pressure going sky-high, or perhaps something more professional sounding. - Rethink this. Do you really really want to encourage vendors to use this raw API instead of them using the proper APIs? > > While this all sounds very powerful it comes with a couple of caveats: > 1. Bug reports using raw commands will not get the same level of > attention as bug reports using supported commands (via taint). > 2. Supported commands will be rejected by the RAW command. > > With this comes new debugfs knob to allow full access to your toes with > your weapon of choice. Problem is that debugfs is no longer "debug" but is enabled in production kernel.
