Re: [RFC PATCH 1/9] cxl/acpi: Add an acpi_cxl module for the CXL interconnect

Randy Dunlap
2020-11-11T06:17:38Z

Hi,

On 11/10/20 9:43 PM, Ben Widawsky wrote:
> ---
> drivers/Kconfig | 1 +
> drivers/Makefile | 1 +
> drivers/cxl/Kconfig | 30 +++++++++++
> drivers/cxl/Makefile | 5 ++
> drivers/cxl/acpi.c | 119 ++++++++++++++++++++++++++++++++++++++++++
> drivers/cxl/acpi.h | 15 ++++++
> include/acpi/actbl1.h | 52 ++++++++++++++++++
> 7 files changed, 223 insertions(+)

> diff --git a/drivers/cxl/Kconfig b/drivers/cxl/Kconfig
> new file mode 100644
> index 000000000000..dd724bd364df
> --- /dev/null
> +++ b/drivers/cxl/Kconfig
> @@ -0,0 +1,30 @@
> +# SPDX-License-Identifier: GPL-2.0-only
> +menuconfig CXL_BUS
> + tristate "CXL (Compute Express Link) Devices Support"
> + help
> + CXL is a bus that is electrically compatible with PCI-E, but layers
> + three protocols on that signalling (CXL.io, CXL.cache, and CXL.mem). The
> + CXL.cache protocol allows devices to hold cachelines locally, the
> + CXL.mem protocol allows devices to be fully coherent memory targets, the
> + CXL.io protocol is equivalent to PCI-E. Say 'y' to enable support for
> + the configuration and management of devices supporting these protocols.
> +
> +if CXL_BUS
> +
> +config CXL_BUS_PROVIDER
> + tristate
> +
> +config CXL_ACPI
> + tristate "CXL Platform Support"
> + depends on ACPI
> + default CXL_BUS

Please provide some justification for something other than the
default default of 'n'. We try hard not to add drivers/modules that
are not required for bootup.

> + select CXL_BUS_PROVIDER
> + help
> + CXL Platform Support is a prerequisite for any CXL device driver that
> + wants to claim ownership of the component register space. By default
> + platform firmware assumes Linux is unaware of CXL capabilities and
> + requires explicit opt-in. This platform component also mediates
> + resources described by the CEDT (CXL Early Discovery Table)

end sentence with '.'

> +
> + Say 'y' to enable CXL (Compute Express Link) drivers.

or 'm'

> +endif

--
~Randy