The bootmenu enumerates the UEFI boot variable and distro boot (boot_targets) for boot device selection.
Signed-off-by: Masahisa Kojima masahisa.kojima@linaro.org --- Newly created in v4
doc/usage/bootmenu.rst | 65 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 65 insertions(+)
diff --git a/doc/usage/bootmenu.rst b/doc/usage/bootmenu.rst index 1f094ad6ed..dc1d22062b 100644 --- a/doc/usage/bootmenu.rst +++ b/doc/usage/bootmenu.rst @@ -93,3 +93,68 @@ When you intend to use the bootmenu on a color frame buffer console, make sure to additionally define::
CONFIG_CFB_CONSOLE_ANSI=y + +UEFI boot variable enumeration +============================== + +The bootmenu automatically generates the UEFI boot variable("BOOT####") +in order of "BootOrder". When the user selects the UEFI boot +variable entry, bootmenu sets the selected boot variable index +to "BootNext", then call the uefi boot manager with the command +"bootefi bootmgr". + +The bootmenu automatically enumerates the possible bootable +media devices supporting EFI_SIMPLE_FILE_SYSTEM_PROTOCOL. + +The bootmenu prints the EFI_LOAD_OPTION.Description[] as title +of the entry together with "UEFI" prefix and BOOT#### variable name. + +Example bootmenu is as below:: + + *** U-Boot Boot Menu *** + + UEFI BOOT0000 : mmc0:1 + UEFI BOOT0001 : mmc0:2 + UEFI BOOT0002 : debian + UEFI BOOT0003 : nvme0:1 + UEFI BOOT0004 : ubuntu + UEFI BOOT0005 : nvme0:2 + UEFI BOOT0006 : usb0:2 + +To scan the discoverable devices connected to the buses such as +USB and PCIe prior to bootmenu showing up, CONFIG_PREBOOT can be +used to run the command before showing the bootmenu, i.e.:: + + CONFIG_USE_PREBOOT=y + CONFIG_PREBOOT="pci enum; usb start; scsi scan; nvme scan; virtio scan" + +distro boot command enumeration +=============================== + +The bootmenu also automatically generates the entries for +distro boot command. The bootmenu shows the devices in boot_targets +environment variable. +When the user selects the distro boot command entry, the bootmenu +runs the command defined in "bootcmd_xxx" environment variable. +As an example, if user selects "usb0" entry, bootmenu runs the +command defined in "bootcmd_usb0". + +Example boot_targets:: + + usb0, scsi0, nvme0, dhcp + +Example bootmenu is as below:: + + *** U-Boot Boot Menu *** + + distro_boot : usb0 + distro_boot : scsi0 + distro_boot : nvme0 + distro_boot : dhcp + +Disable to enter the U-Boot console +=================================== + +To improve the product security, U-Boot console can be disabled by:: + + CONFIG_CMD_BOOTMENU_ENTER_UBOOT_CONSOLE=n