Re: [PATCH v3 06/10] fwctl: Add documentation

Jonathan Cameron
2024-08-23T14:35:17Z

On Wed, 21 Aug 2024 15:10:58 -0300
Jason Gunthorpe <jgg@nvidia.com> wrote:

> Document the purpose and rules for the fwctl subsystem.
>
> Link in kdocs to the doc tree.
>
> Nacked-by: Jakub Kicinski <kuba@kernel.org>
> Link: https://lore.kernel.org/r/20240603114250.5325279c@kernel.org
> Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> https://lore.kernel.org/r/ZrHY2Bds7oF7KRGz@phenom.ffwll.local
> Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Just one trivial plural / singular comment.
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

> ---
> Documentation/userspace-api/fwctl.rst | 285 ++++++++++++++++++++++++++
> Documentation/userspace-api/index.rst | 1 +
> 2 files changed, 286 insertions(+)
> create mode 100644 Documentation/userspace-api/fwctl.rst
>
> diff --git a/Documentation/userspace-api/fwctl.rst b/Documentation/userspace-api/fwctl.rst
> new file mode 100644
> index 00000000000000..8f3da30ee7c91b
> --- /dev/null
> +++ b/Documentation/userspace-api/fwctl.rst
> @@ -0,0 +1,285 @@
> +.. SPDX-License-Identifier: GPL-2.0
> +
> +===============
> +fwctl subsystem
> +===============
> +
> +:Author: Jason Gunthorpe
> +
> +Overview
> +========
> +
> +Modern devices contain extensive amounts of FW, and in many cases, are largely
> +software-defined pieces of hardware. The evolution of this approach is largely a
> +reaction to Moore's Law where a chip tape out is now highly expensive, and the
> +chip design is extremely large. Replacing fixed HW logic with a flexible and
> +tightly coupled FW/HW combination is an effective risk mitigation against chip
> +respin. Problems in the HW design can be counteracted in device FW. This is
> +especially true for devices which present a stable and backwards compatible
> +interface to the operating system driver (such as NVMe).
> +
> +The FW layer in devices has grown to incredible sizes and devices frequently
incredible size
(tricky to get the plurals right in this sentence, but currently its a mixture)
> +integrate clusters of fast processors to run it. For example, mlx5 devices have
> +over 30MB of FW code, and big configurations operate with over 1GB of FW managed
> +runtime state.
...