> From: AKASHI Takahiro <takahiro.aka...@linaro.org> > Date: Tue, 9 Nov 2021 10:32:32 +0900
Hi Takahiro, > Under the current implementation, booting from removal 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 > 1) 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 ... > > 2) 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 The problem with this approach is that EFI device paths are complicated things and I don't think we can expect users to do what you describe above all by hand. All x86 machines I've seen have a more user-friendly way to configure the desired boot order, and also a way to specify which device to boot from after automatic boot has been interrupted. With the current distroboot scripts one can simply do: setenv boot_targets usb0 mmc0 pxe dhcp and I think we need to have something simple like that. Maybe the code can automatically create Boot#### and BootOrder variables based on the boot_targets environment variables if they're not defined? Another idea is to accept U-Boot device names (e.g. usb0, mmc0) as aliases for EFI device paths and automatically expand them? > Signed-off-by: AKASHI Takahiro <takahiro.aka...@linaro.org> > --- > lib/efi_loader/efi_bootmgr.c | 65 +++++++++++++++++++++++++++++++++++- > 1 file changed, 64 insertions(+), 1 deletion(-) > > diff --git a/lib/efi_loader/efi_bootmgr.c b/lib/efi_loader/efi_bootmgr.c > index 1fe19237f9a6..1d9d5858561f 100644 > --- a/lib/efi_loader/efi_bootmgr.c > +++ b/lib/efi_loader/efi_bootmgr.c > @@ -30,6 +30,66 @@ static const struct efi_runtime_services *rs; > * should do normal or recovery boot. > */ > > +#if defined(CONFIG_ARM64) > +#define BOOTEFI_NAME "bootaa64.efi" > +#elif defined(CONFIG_ARM) > +#define BOOTEFI_NAME "bootarm.efi" > +#elif defined(CONFIG_X86_RUN_32BIT) > +#define BOOTEFI_NAME "bootia32.efi" > +#elif defined(CONFIG_X86_RUN_64BIT) > +#define BOOTEFI_NAME "bootx64.efi" > +#elif defined(CONFIG_ARCH_RV32I) > +#define BOOTEFI_NAME "bootriscv32.efi" > +#elif defined(CONFIG_ARCH_RV64I) > +#define BOOTEFI_NAME "bootriscv64.efi" > +#else > +#define BOOTEFI_NAME "dummy.efi" > +#endif > + > +/** > + * expand_media_path() - expand a device path for default file name > + * @device_path: device path to check against > + * > + * If @device_path is a media or disk partition which houses a file > + * system, this function returns a full device path which contains > + * an architecture-specific default file name for removable media. > + * > + * Return: a newly allocated device path > + */ > +static > +struct efi_device_path *expand_media_path(struct efi_device_path > *device_path) > +{ > + struct efi_device_path *dp, *full_path; > + efi_handle_t handle; > + efi_status_t ret; > + > + if (!device_path) > + return NULL; > + > + /* > + * If device_path is a (removable) media or partition which provides > + * simple file system protocol, append a default file name to support > + * booting from removable media. > + */ > + dp = device_path; > + ret = efi_locate_device_path(&efi_simple_file_system_protocol_guid, > + &dp, &handle); > + if (ret == EFI_SUCCESS) { > + if (dp->type == DEVICE_PATH_TYPE_END) { > + dp = efi_dp_from_file(NULL, 0, > + "/efi/boot/" BOOTEFI_NAME); > + full_path = efi_dp_append(device_path, dp); > + } else { > + full_path = efi_dp_dup(device_path); > + } > + efi_free_pool(dp); > + } else { > + full_path = efi_dp_dup(device_path); > + } > + > + return full_path; > +} > + > /** > * try_load_entry() - try to load image for boot option > * > @@ -68,13 +128,16 @@ static efi_status_t try_load_entry(u16 n, efi_handle_t > *handle, > } > > if (lo.attributes & LOAD_OPTION_ACTIVE) { > + struct efi_device_path *file_path; > u32 attributes; > > log_debug("%s: trying to load \"%ls\" from %pD\n", > __func__, lo.label, lo.file_path); > > - ret = EFI_CALL(efi_load_image(true, efi_root, lo.file_path, > + file_path = expand_media_path(lo.file_path); > + ret = EFI_CALL(efi_load_image(true, efi_root, file_path, > NULL, 0, handle)); > + efi_free_pool(file_path); > if (ret != EFI_SUCCESS) { > log_warning("Loading %ls '%ls' failed\n", > varname, lo.label); > -- > 2.33.0 > >