Re: [PATCH v5 10/15] cxl: Add support for fwctl RPC command to enable CXL feature commands

[Jason Gunthorpe <jgg@nvidia.com>]

On Wed, Feb 12, 2025 at 06:49:23PM -0800, Saeed Mahameed wrote:

> > +/**
> > + * struct fwctl_rpc_cxl - ioctl(FWCTL_RPC) input for CXL
> > + * @opcode: CXL mailbox command opcode
> > + * @flags: Flags for the command (input).
> > + * @op_size: Size of input payload.
> > + * @reserved1: Reserved. Must be 0s.
> > + * @in_payload: User address of the hardware op input structure
> > + */
> > +struct fwctl_rpc_cxl {
> > +	__u32 opcode;
> > +	__u32 flags;
> > +	__u32 op_size;
> > +	__u32 reserved1;
> > +	__aligned_u64 in_payload;
> 
> I think this would be an unnecessary indirection.
> fwctl subsystem already copies the user buffer for you.

Yes, the idea was the whole command would be in here:

struct fwctl_rpc {
	__u32 size;
	__u32 scope;
	__u32 in_len;
	__u32 out_len;
	__aligned_u64 in;
^^^

Why do you need to split into two parts?

Jason