> From: Masahisa Kojima <masahisa.koj...@linaro.org>
> Date: Thu, 28 Apr 2022 17:09:33 +0900
>
> This patch series adds the menu-driven boot device selection,
> by extending the existing "bootmenu" to include UEFI and distro_boot
> related entries, and supports menu-driven UEFI boot variable
> maintenance.
>
> This patch series also includes the removable media support
> that UEFI specification requires to support.
>
> The menu example is as follows.
>
> *** U-Boot Boot Menu ***
>
> bootmenu_00 : Boot 1. kernel
> bootmenu_01 : Boot 2. kernel
> bootmenu_02 : Reset board
> UEFI BOOT0000 : debian
> UEFI BOOT0001 : ubuntu
> UEFI BOOT0002 : mmc0:1
> UEFI BOOT0003 : mmc0:2
> UEFI BOOT0004 : nvme0:1
> UEFI BOOT0005 : nvme0:2
> UEFI BOOT0006 : usb0:2
> UEFI BOOT0007 : usb1:1
> UEFI BOOT0008 : usb1:2
> distro_boot : usb0
> distro_boot : scsi0
> distro_boot : virtio0
> distro_boot : dhcp
>
> Press UP/DOWN to move, ENTER to select, ESC/CTRL+C to quit
>
> [How to run on QEMU(arm64)]
> 1) clone source code
> $ git clone https://git.linaro.org/people/masahisa.kojima/u-boot.git \
> -b kojima/bootmenu_v5_upstream_0428 --depth 1
>
> 2) prepare U-Boot .config
> $ make qemu_arm64_menuconfig
> then, enable CONFIG_CMD_BOOTMENU and CONFIG_AUTOBOOT_MENU_SHOW
So when I do this on a Apple M1 system it ends up doing something
weird. With CONFIG_AUTOBOOT_MENU_SHOW=y, it shows the boot menu and
then automaticaly selects the "UEFI Boot Manager Maintenance" option
after the boot delay expires. That is a bit weird. Initially I
expected it to fall through into the normal distro_bootcmd script by
executing bootcmd.
Now this happens because NVMe isn't probed automatically. So no
viable boot options are found. But distro_boot explicitly probes NVMe
if CONFIG_NVME is enabled (see include/config_distro_bootcmd.h). So
falling through into the distro boot would actually have worked.
Another surprise is that the default boot order seems to depend on the
order in which devices are probed. With:
CONFIG_PREBOOT="nvme scan; usb start"
it boots from NVMe by default, and with:
CONFIG_PREBOOT="usb start; nvme scan"
it boots from USB by default, despite the fact that in
include/configs/apple.h I have:
#define BOOT_TARGET_DEVICES(func) \
BOOT_TARGET_NVME(func) \
BOOT_TARGET_USB(func)
If I change the boot order through the "UEFI Boot Manager Maintenance"
option, it seems that the new boot order only persists if I actually
boot into the OS. When I reset the board before doing that it keeps
the old boot order.
Last but not least, it seems that
CONFIG_CMD_BOOTMENU_ENTER_UBOOT_CONSOLE is disabled by default despite
the fact that doc/usage/cmd/bootmenu.rst suggests the opposite. I
think the default for that option should be "y" otherwise I fear a lot
of boards will end up with shipping with a U-Boot with no way for
users to get at the u-boot prompt.
All in all, I don't think any of this is a show-stopper. It just
needs some further polishing, which probably is best done after this
lands (except for the CMD_BOOTMENU_ENTER_UBOOT_CONSOLE thing). It
does make it possible for me to use the EFI bootmgr on Apple M1
systems and it definitely improves the user interface for naive users.
