Re: [PATCH v5 5/9] cxl/mem: Add a "RAW" send command

Konrad Rzeszutek Wilk
2021-02-20T01:06:32Z

On Tue, Feb 16, 2021 at 08:09:54PM -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. The primary use for this
> command is to [begrudgingly] allow undocumented vendor specific hardware
> commands.
>
> While not the main motivation, it also allows prototyping new hardware
> commands without a driver patch and rebuild.
>
> 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.
>
> Cc: Ariel Sibley <Ariel.Sibley@microchip.com>
> Signed-off-by: Ben Widawsky <ben.widawsky@intel.com>
> Reviewed-by: Dan Williams <dan.j.williams@intel.com> (v2)
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>