Re: [PATCH 04/14] firmware_loader: add built-in firmware kconfig entry

[Greg KH <gregkh@linuxfoundation.org>]

On Fri, Sep 17, 2021 at 11:22:16AM -0700, Luis R. Rodriguez wrote:
> From: Luis Chamberlain <mcgrof@kernel.org>
> 
> The built-in firmware is always supported when a user enables
> FW_LOADER=y today, that is, it is built-in to the kernel. When the
> firmware loader is built as a module, support for built-in firmware
> is skipped. This requirement is not really clear to users or even
> developers.
> 
> Also, by default the EXTRA_FIRMWARE is always set to an empty string
> and so by default we really have nothing built-in to that kernel's
> sections for built-in firmware, so today a all FW_LOADER=y kernels
> spins their wheels on an empty set of built-in firmware for each
> firmware request with no true need for it.
> 
> Add a new kconfig entry to represent built-in firmware support more
> clearly. This let's knock 3 birds with one stone:
> 
>  o Clarifies that support for built-in firmware requires the
>    firmware loader to be built-in to the kernel
> 
>  o By default we now always skip built-in firmware even if a FW_LOADER=y
> 
>  o This also lets us make it clear that the EXTRA_FIRMWARE_DIR
>    kconfig entry is only used for built-in firmware
> 
> Reviewed-by: Borislav Petkov <bp@suse.de>
> Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
> ---
>  .../driver-api/firmware/built-in-fw.rst       |  2 ++
>  Documentation/x86/microcode.rst               |  5 ++--
>  drivers/base/firmware_loader/Kconfig          | 25 +++++++++++++------
>  drivers/base/firmware_loader/Makefile         |  3 +--
>  drivers/base/firmware_loader/main.c           |  4 +--
>  5 files changed, 26 insertions(+), 13 deletions(-)
> 
> diff --git a/Documentation/driver-api/firmware/built-in-fw.rst b/Documentation/driver-api/firmware/built-in-fw.rst
> index bc1c961bace1..9dd2b1df44f0 100644
> --- a/Documentation/driver-api/firmware/built-in-fw.rst
> +++ b/Documentation/driver-api/firmware/built-in-fw.rst
> @@ -8,6 +8,7 @@ the filesystem. Instead, firmware can be looked for inside the kernel
>  directly. You can enable built-in firmware using the kernel configuration
>  options:
>  
> +  * CONFIG_FW_LOADER_BUILTIN
>    * CONFIG_EXTRA_FIRMWARE
>    * CONFIG_EXTRA_FIRMWARE_DIR
>  
> @@ -17,6 +18,7 @@ into the kernel with CONFIG_EXTRA_FIRMWARE:
>  * Speed
>  * Firmware is needed for accessing the boot device, and the user doesn't
>    want to stuff the firmware into the boot initramfs.
> +* Testing built-in firmware
>  
>  Even if you have these needs there are a few reasons why you may not be
>  able to make use of built-in firmware:
> diff --git a/Documentation/x86/microcode.rst b/Documentation/x86/microcode.rst
> index a320d37982ed..d199f0b98869 100644
> --- a/Documentation/x86/microcode.rst
> +++ b/Documentation/x86/microcode.rst
> @@ -114,11 +114,12 @@ Builtin microcode
>  =================
>  
>  The loader supports also loading of a builtin microcode supplied through
> -the regular builtin firmware method CONFIG_EXTRA_FIRMWARE. Only 64-bit is
> -currently supported.
> +the regular builtin firmware method using CONFIG_FW_LOADER_BUILTIN and
> +CONFIG_EXTRA_FIRMWARE. Only 64-bit is currently supported.
>  
>  Here's an example::
>  
> +  CONFIG_FW_LOADER_BUILTIN=y
>    CONFIG_EXTRA_FIRMWARE="intel-ucode/06-3a-09 amd-ucode/microcode_amd_fam15h.bin"
>    CONFIG_EXTRA_FIRMWARE_DIR="/lib/firmware"
>  
> diff --git a/drivers/base/firmware_loader/Kconfig b/drivers/base/firmware_loader/Kconfig
> index 5b24f3959255..de4fcd9d41f3 100644
> --- a/drivers/base/firmware_loader/Kconfig
> +++ b/drivers/base/firmware_loader/Kconfig
> @@ -29,8 +29,10 @@ if FW_LOADER
>  config FW_LOADER_PAGED_BUF
>  	bool
>  
> -config EXTRA_FIRMWARE
> -	string "Build named firmware blobs into the kernel binary"
> +config FW_LOADER_BUILTIN
> +	bool "Enable support for built-in firmware"
> +	default n

n is always the default, no need to list it again.

> +	depends on FW_LOADER=y

I don't see what this gets us to add another config option.  Are you
making things easier later on?

Anyway, I took the first 3 patches here, please fix this up and rebase
and resend.

thanks,

greg k-h