[U-Boot] [PATCH 14/16] efi_loader: Add distro boot script for removable media

[Leif Lindholm <leif.lindholm@linaro.org>]

On Tue, Feb 02, 2016 at 03:45:12AM +0100, Alexander Graf wrote:
> UEFI defines a simple boot protocol for removable media. There we should look
> at the EFI (first GPT FAT) partition and search for /efi/boot/bootXXX.efi with
> XXX being different between different platforms (x86, x64, arm, aa64, ...).

One comment, one question.
Comment:
It's not really "the first GPT FAT" - it's the partition marked with
the EFI System Partition type (containing a FAT filesystem).
This is actually defined for MBR partition tables too, but I'd be
quite happy for that bit of legacy to be left out.

Question:
Does U-Boot support El Torito for iso images?

> 
> This patch implements a simple version of that protocol for the default distro
> boot script. With this we can automatically boot from valid UEFI enabled
> removable media.
> 
> Because from all I could see U-Boot by default doesn't deliver device tree
> blobs with its firmware, we also need to load the dtb from somewhere. Traverse
> the same EFI partition for an fdt file that fits our current board so that
> an OS receives a valid device tree when booted automatically.
> 
> Signed-off-by: Alexander Graf <agraf@suse.de>
> Reviewed-by: Simon Glass <sjg@chromium.org>
> ---
>  include/config_distro_bootcmd.h | 47 ++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 46 insertions(+), 1 deletion(-)
> 
> diff --git a/include/config_distro_bootcmd.h b/include/config_distro_bootcmd.h
> index 37c6b43..c19f1b0 100644
> --- a/include/config_distro_bootcmd.h
> +++ b/include/config_distro_bootcmd.h
> @@ -90,6 +90,48 @@
>  	BOOT_TARGET_DEVICES_references_UBIFS_without_CONFIG_CMD_UBIFS
>  #endif
>  
> +#ifdef CONFIG_EFI_LOADER
> +#if defined(CONFIG_ARM64)
> +#define BOOTEFI_NAME "bootaa64.efi"
> +#elif defined(CONFIG_ARM)
> +#define BOOTEFI_NAME "bootarm.efi"
> +#endif
> +#endif
> +
> +#ifdef BOOTEFI_NAME
> +#define BOOTENV_SHARED_EFI                                                \
> +	"boot_efi_binary="                                                \
> +		"load ${devtype} ${devnum}:${distro_bootpart} "           \
> +			"${kernel_addr_r} efi/boot/"BOOTEFI_NAME"; "      \
> +		"bootefi ${kernel_addr_r}\0"                              \
> +	\
> +	"load_efi_dtb="                                                   \
> +		"load ${devtype} ${devnum}:${distro_bootpart} "           \
> +			"${fdt_addr_r} ${prefix}${fdt_name}; "           \
> +		"fdt addr ${fdt_addr_r}\0"                                \
> +	\
> +	"efi_dtb_prefixes=/ /dtb/ /dtb/current/\0"                        \
> +	"scan_dev_for_efi="                                               \
> +		"for prefix in ${efi_dtb_prefixes}; do "                  \
> +			"if test -e ${devtype} "                          \
> +					"${devnum}:${distro_bootpart} "   \
> +					"${prefix}${fdt_name}; then "     \
> +				"run load_efi_dtb; "                      \
> +			"fi;"                                             \
> +		"done;"                                                   \
> +		"if test -e ${devtype} ${devnum}:${distro_bootpart} "     \
> +					"efi/boot/"BOOTEFI_NAME"; then "  \
> +				"echo Found EFI removable media binary "  \
> +					"efi/boot/"BOOTEFI_NAME"; "       \
> +				"run boot_efi_binary; "                   \
> +				"echo EFI LOAD FAILED: continuing...; "   \
> +		"fi; "
> +#define SCAN_DEV_FOR_EFI "run scan_dev_for_efi;"
> +#else
> +#define BOOTENV_SHARED_EFI
> +#define SCAN_DEV_FOR_EFI
> +#endif
> +
>  #ifdef CONFIG_CMD_SATA
>  #define BOOTENV_SHARED_SATA	BOOTENV_SHARED_BLKDEV(sata)
>  #define BOOTENV_DEV_SATA	BOOTENV_DEV_BLKDEV
> @@ -217,6 +259,7 @@
>  	BOOTENV_SHARED_SCSI \
>  	BOOTENV_SHARED_IDE \
>  	BOOTENV_SHARED_UBIFS \
> +	BOOTENV_SHARED_EFI \
>  	"boot_prefixes=/ /boot/\0" \
>  	"boot_scripts=boot.scr.uimg boot.scr\0" \
>  	"boot_script_dhcp=boot.scr.uimg\0" \
> @@ -258,7 +301,9 @@
>  		"for prefix in ${boot_prefixes}; do "                     \
>  			"run scan_dev_for_extlinux; "                     \
>  			"run scan_dev_for_scripts; "                      \
> -		"done\0"                                                  \
> +		"done;"                                                   \
> +		SCAN_DEV_FOR_EFI                                          \
> +		"\0"                                                      \
>  	\
>  	"scan_dev_for_boot_part="                                         \
>  		"part list ${devtype} ${devnum} -bootable devplist; "     \
> -- 
> 2.6.2
>