Re: [RFC PATCH 3/9] cxl/mem: Add a driver for the type-3 mailbox

From: Randy Dunlap <rdunlap@infradead.org>
To: Ben Widawsky <ben.widawsky@intel.com>, linux-cxl@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org,
	linux-acpi@vger.kernel.org,
	Dan Williams <dan.j.williams@intel.com>,
	Ira Weiny <ira.weiny@intel.com>,
	Vishal Verma <vishal.l.verma@intel.com>,
	"Kelley, Sean V" <sean.v.kelley@intel.com>,
	Bjorn Helgaas <bhelgaas@google.com>,
	"Rafael J . Wysocki" <rafael.j.wysocki@intel.com>
Subject: Re: [RFC PATCH 3/9] cxl/mem: Add a driver for the type-3 mailbox
Date: Tue, 10 Nov 2020 22:17:08 -0800	[thread overview]
Message-ID: <1dbfc3a3-5f81-90b2-5b0b-5dcb99e2eecd@infradead.org> (raw)
In-Reply-To: <20201111054356.793390-4-ben.widawsky@intel.com>

Hi,

On 11/10/20 9:43 PM, Ben Widawsky wrote:
> ---
>  drivers/cxl/Kconfig  | 20 +++++++++++
>  drivers/cxl/Makefile |  2 ++
>  drivers/cxl/mem.c    | 82 ++++++++++++++++++++++++++++++++++++++++++++
>  drivers/cxl/pci.h    | 15 ++++++++
>  4 files changed, 119 insertions(+)

> diff --git a/drivers/cxl/Kconfig b/drivers/cxl/Kconfig
> index dd724bd364df..15548f5c77ff 100644
> --- a/drivers/cxl/Kconfig
> +++ b/drivers/cxl/Kconfig
> @@ -27,4 +27,24 @@ config CXL_ACPI
>  	  resources described by the CEDT (CXL Early Discovery Table)
>  
>  	  Say 'y' to enable CXL (Compute Express Link) drivers.
> +
> +config CXL_MEM
> +        tristate "CXL.mem Device Support"
> +        depends on PCI && CXL_BUS_PROVIDER != n
> +        default m if CXL_BUS_PROVIDER

The "if CXL_BUS_PROVIDER" should be redundant due to the "depends on" clause.
However, having any default or 'm' or 'y' needs to be justified.

> +        help
> +          The CXL.mem protocol allows a device to act as a provider of
> +          "System RAM" and/or "Persistent Memory" that is fully coherent
> +          as if the memory was attached to the typical CPU memory
> +          controller.
> +
> +          Say 'y/m' to enable a driver named "cxl_mem.ko" that will attach

The builtin driver will not be named cxl-mem.ko.

> +          to CXL.mem devices for configuration, provisioning, and health
> +          monitoring, the so called "type-3 mailbox". Note, this driver
> +          is required for dynamic provisioning of CXL.mem attached
> +          memory, a pre-requisite for persistent memory support, but

	               prerequisite

> +          devices that provide volatile memory may be fully described by
> +          existing platform firmware memory enumeration.
> +
> +          If unsure say 'n'.
>  endif

-- 
~Randy