[PATCH] efi_loader: fix efi_bootmgr_enumerate_boot_option

[Mark Kettenis]

> From: Heinrich Schuchardt <heinrich.schuchardt at canonical.com>
> Date: Tue, 17 Oct 2023 19:51:48 +0200
> 
> Only auto-generate boot options for removable media.
> 
> For testing the different handling of removable and non-removable devices
> an emulated USB device can be used:
> 
>     make qemu-riscv64_smode_defconfig; make
>     qemu-system-riscv64 -M virt -kernel u-boot.bin -nographic \
>     -device qemu-xhci -drive if=none,file=disk.img,format=raw,id=USB1 \
>     -device usb-storage,drive=USB1,removable=on

Unless I misunderstand what this patch does, this may result in
systems that don't boot after installation.

On most boards U-Boot does not provide a way to create persistent EFI
variables after ExitBootServices() is called.  This means that an OS
installer cannot create a boot entry for the OS installation it just
created.  Therefore the EFI boot manager will not boot the newly
installed system.

Now as long as the traditional distro boot mechanism or the EFI distro
boot bootmeth is enabled the system will probobly still attempt to
boot the installed system.  But do want to rely on that?

> Fixes: c416f1c0bcab ("bootmenu: add removable media entries")
> Fixes: 339b527bd450 ("Move bootorder and bootoption apis to lib")
> Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt at canonical.com>
> ---
>  lib/efi_loader/efi_bootmgr.c | 10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/lib/efi_loader/efi_bootmgr.c b/lib/efi_loader/efi_bootmgr.c
> index a40762c74c..96d45157b3 100644
> --- a/lib/efi_loader/efi_bootmgr.c
> +++ b/lib/efi_loader/efi_bootmgr.c
> @@ -346,7 +346,7 @@ error:
>  }
>  
>  /**
> - * efi_bootmgr_enumerate_boot_option() - enumerate the possible bootable media
> + * efi_bootmgr_enumerate_boot_option() - boot options for removable boot media
>   *
>   * @opt:		pointer to the media boot option structure
>   * @volume_handles:	pointer to the efi handles
> @@ -370,6 +370,9 @@ static efi_status_t efi_bootmgr_enumerate_boot_option(struct eficonfig_media_boo
>  		struct efi_device_path *device_path;
>  		struct efi_device_path *short_dp;
>  
> +		if (!efi_disk_is_removable(volume_handles[i]))
> +			continue;
> +
>  		ret = efi_search_protocol(volume_handles[i], &efi_guid_device_path, &handler);
>  		if (ret != EFI_SUCCESS)
>  			continue;
> @@ -674,7 +677,10 @@ efi_status_t efi_bootmgr_update_media_device_boot_option(void)
>  		goto out;
>  	}
>  
> -	/* enumerate all devices supporting EFI_SIMPLE_FILE_SYSTEM_PROTOCOL */
> +	/*
> +	 * Enumerate all removable devices supporting the
> +	 * EFI_SIMPLE_FILE_SYSTEM_PROTOCOL.
> +	 */
>  	ret = efi_bootmgr_enumerate_boot_option(opt, volume_handles, count);
>  	if (ret != EFI_SUCCESS)
>  		goto out;
> -- 
> 2.40.1
> 
>