[PATCH 1/4] efi_loader: description EFI_LOAD_FILE2_PROTOCOL

[Ilias Apalodimas]

On Sat, Oct 03, 2020 at 01:57:13PM +0200, Heinrich Schuchardt wrote:
> U-Boot offers a EFI_LOAD_FILE2_PROTOCOL which the Linux EFI stub can use to
> load an initial RAM disk. Update the function comments of the
> implementation.
> 
> Signed-off-by: Heinrich Schuchardt <xypron.glpk at gmx.de>
> ---
>  lib/efi_loader/efi_load_initrd.c | 42 +++++++++++++++++---------------
>  1 file changed, 23 insertions(+), 19 deletions(-)
> 
> diff --git a/lib/efi_loader/efi_load_initrd.c b/lib/efi_loader/efi_load_initrd.c
> index 574a83d7e3..ff69e6eb79 100644
> --- a/lib/efi_loader/efi_load_initrd.c
> +++ b/lib/efi_loader/efi_load_initrd.c
> @@ -47,9 +47,9 @@ static const struct efi_initrd_dp dp = {
>  /**
>   * get_file_size() - retrieve the size of initramfs, set efi status on error
>   *
> - * @dev:			device to read from. i.e "mmc"
> - * @part:			device partition. i.e "0:1"
> - * @file:			name fo file
> + * @dev:			device to read from, e.g. "mmc"
> + * @part:			device partition, e.g. "0:1"
> + * @file:			name of file
>   * @status:			EFI exit code in case of failure
>   *
>   * Return:			size of file
> @@ -78,15 +78,16 @@ out:
>  }
> 
>  /**
> - * load_file2() - get information about random number generation
> + * efi_load_file2initrd() - load initial RAM disk
> + *
> + * This function implements the LoadFile service of the EFI_LOAD_FILE2_PROTOCOL
> + * in order to load an initial RAM disk requested by the Linux kernel stub.
>   *
> - * This function implement the LoadFile2() service in order to load an initram
> - * disk requested by the Linux kernel stub.
>   * See the UEFI spec for details.
>   *
> - * @this:			loadfile2 protocol instance
> - * @file_path:			relative path of the file. "" in this case
> - * @boot_policy:		must be false for Loadfile2
> + * @this:			EFI_LOAD_FILE2_PROTOCOL instance
> + * @file_path:			media device path of the file, "" in this case
> + * @boot_policy:		must be false
>   * @buffer_size:		size of allocated buffer
>   * @buffer:			buffer to load the file
>   *
> @@ -128,7 +129,13 @@ efi_load_file2_initrd(struct efi_load_file_protocol *this,
>  		goto out;
>  	}
> 
> -	/* expect something like 'mmc 0:1 initrd.cpio.gz' */
> +	/*
> +	 * expect a string with three space separated parts:
> +	 *
> +	 * * a block device type, e.g. "mmc"
> +	 * * a device and partition identifier, e.g. "0:1"
> +	 * * a file path on the block device, e.g. "/boot/initrd.cpio.gz"
> +	 */
>  	dev = strsep(&s, " ");
>  	if (!dev)
>  		goto out;
> @@ -168,23 +175,20 @@ out:
>  }
> 
>  /**
> - * efi_initrd_register() - Register a handle and loadfile2 protocol
> + * efi_initrd_register() - create handle for loading initial RAM disk
>   *
> - * This function creates a new handle and installs a linux specific GUID
> - * to handle initram disk loading during boot.
> - * See the UEFI spec for details.
> + * This function creates a new handle and installs a Linux specific vendor
> + * device path and an EFI_LOAD_FILE_2_PROTOCOL. Linux uses the device path
> + * to identify the handle and then calls the LoadFile service of the
> + * EFI_LOAD_FILE_2_PROTOCOL to read the initial RAM disk.
>   *
> - * Return:			status code
> + * Return:	status code
>   */
>  efi_status_t efi_initrd_register(void)
>  {
>  	efi_handle_t efi_initrd_handle = NULL;
>  	efi_status_t ret;
> 
> -	/*
> -	 * Set up the handle with the EFI_LOAD_FILE2_PROTOCOL which Linux may
> -	 * use to load the initial ramdisk.
> -	 */
>  	ret = EFI_CALL(efi_install_multiple_protocol_interfaces
>  		       (&efi_initrd_handle,
>  			/* initramfs */
> --
> 2.28.0
> 

Reviewed-by: Ilias Apalodimas <ilias.apalodimas at linaro.org>