Kojima-san,
On Thu, 31 Mar 2022 at 03:51, Masahisa Kojima masahisa.kojima@linaro.org wrote:
Hi Ilias,
On Thu, 31 Mar 2022 at 04:13, Ilias Apalodimas ilias.apalodimas@linaro.org wrote:
Hello Akashi-san,
On Thu, Mar 24, 2022 at 10:54:38PM +0900, Masahisa Kojima wrote:
From: AKASHI Takahiro takahiro.akashi@linaro.org
Under the current implementation, booting from removable media using a architecture-specific default image name, say BOOTAA64.EFI, is supported only in distro_bootcmd script. See the commit 74522c898b35 ("efi_loader: Add distro boot script for removable media").
This is, however, half-baked implementation because
- UEFI specification requires this feature to be implemented as part of Boot Manager's responsibility:
3 - Boot Manager 3.5.1 Boot via the Simple File Protocol When booting via the EFI_SIMPLE_FILE_SYSTEM_PROTOCOL, the FilePath will start with a device path that points to the device that implements the EFI_SIMPLE_FILE_SYSTEM_PROTOCOL or the EFI_BLOCK_IO_PROTOCOL. The next part of the FilePath may point to the file name, including subdirectories, which contain the bootable image. If the file name is a null device path, the file name must be generated from the rules defined below. ... 3.5.1.1 Removable Media Boot Behavior To generate a file name when none is present in the FilePath, the firmware must append a default file name in the form \EFI\BOOT\BOOT{machine type short-name}.EFI ...
- So (1) entails the hehavior that the user's preference of boot media order should be determined by Boot#### and BootOrder variables.
With this patch, the semantics mentioned above is fully implemented. For example, if you want to boot the system from USB and SCSI in this order,
- define Boot0001 which contains only a device path to the USB device (without any file path/name)
- define Boot0002 which contains only a device path to the SCSI device,
and
- set BootOrder to Boot0001:Boot0002
Mark had some concerns wrt to this approach and from what I can tell this hasn't changed in this revision [1]. Can we use boot_targets and generate Boot#### with an empty FilePath as Mark suggested? Or is the user expected to select that somehow from the menu?
[1] https://lore.kernel.org/u-boot/d3cac2e5b37f96b5@bloch.sibelius.xs4all.nl/
My patch series tries to resolve the above issue to some extent by a different approach.
The patch "[PATCH v4 10/11] bootmenu: add removable media entries" [*1] enumerates the all (removable) medias supporting EFI_SIMPLE_FILE_SYSTEM_PROTOCOL.
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 : usb0:2mmcX:X, usbX:X and nvmeX:X are the entries of the removable media having device path without FilePath. They are automatically created by the bootmenu and BOOT#### and BootOrder variables are updated. They are also managed by the bootmenu, if the usb device is removed from the system at the next boot, the BOOT#### variable is removed by bootmenu and BootOrder is also updated.
[*1] https://lore.kernel.org/u-boot/20220324135443.1571-11-masahisa.kojima@linaro...
Great thanks, that sounds reasonable. I'll go through the rest of the series and let you know /Ilias
Thanks, Masahisa Kojima