[PATCH v2 0/8] efi_loader: improve device-tree loading

[Heinrich Schuchardt]

On 05.06.24 15:17, Simon Glass wrote:
> Hi Heinrich,
> 
> On Wed, 5 Jun 2024 at 02:40, Heinrich Schuchardt
> <heinrich.schuchardt at canonical.com> wrote:
>>
>> On 29.05.24 18:30, Simon Glass wrote:
>>> Hi,
>>>
>>> On Tue, 28 May 2024 at 18:38, E Shattow <lucent at gmail.com> wrote:
>>>>
>>>> Hi,
>>>>
>>>> On Tue, May 28, 2024 at 7:43 AM Heinrich Schuchardt
>>>> <heinrich.schuchardt at canonical.com> wrote:
>>>>>
>>>>> In U-Boot EFI boot options can already specify both an EFI binary and
>>>>> an initrd. With this series we can additionally define the matching
>>>>> device-tree to be loaded in the boot option.
>>>>>
>>>>> With the last patch the boot manager will fall back the device-tree
>>>>> specified by $fdtfile in directories '/dtb/', '/', or '/dtb/current/'
>>>>> on the boot device if no device-tree is specified in the boot
>>>>> option or via a bootefi command parameter.
>>>>>
>>>>
>>>> As tested the $fdtfile environment variable has no effect on
>>>> global EFI boot when i.e. EFI/BOOT/BOOTRISCV64.EFI
>>>> on EFI System Partition and no user-added boot option;
>>>> $fdtfile env variable is not used with "mmc 0" or whichever
>>>> global boot option is enabled by default in the boot order.
>>>>
>>>> Adding a boot option for EFI/BOOT/BOOTRISCV64.EFI
>>>> and giving this priority in the boot order allows $fdtfile to
>>>> be effective here. This is consistent with what is described
>>>> by the series. Would the global EFI boot also get support
>>>> for $fdtfile either with this or a later series?
>>>>
>>>>> v2:
>>>>>           Update efi_dp_concat() instead of new function efi_dp_merge().
>>>>>           Carve out a function efi_load_option_dp_join() which we can
>>>>>           use both for the eficonfig and the efidebug command.
>>>>>           Rename variables id_dp, final_dp_size.
>>>>>           Rename create_initrd_dp() to create_lo_dp_part().
>>>>>           Use enum as parameter for create_lo_dp_part().
>>>>>           Put all related changes into one patch.
>>>>>
>>>>> Heinrich Schuchardt (8):
>>>>>     efi_loader: allow concatenation with contained end node
>>>>>     cmd: eficonfig: add support for setting fdt
>>>>>     cmd: efidebug: add support for setting fdt
>>>>>     efi_loader: load device-tree specified in boot option
>>>>>     efi_loader: move distro_efi_get_fdt_name()
>>>>>     efi_loader: return binary from efi_dp_from_lo()
>>>>>     efi_loader: export efi_load_image_from_path
>>>>>     efi_loader: load distro dtb in bootmgr
>>>>>
>>>>>    boot/bootmeth_efi.c                        |  60 +---------
>>>>>    cmd/eficonfig.c                            |  83 +++++++++----
>>>>>    cmd/efidebug.c                             | 130 +++++++++++++++------
>>>>>    include/efi_loader.h                       |  24 +++-
>>>>>    lib/efi_loader/Makefile                    |   1 +
>>>>>    lib/efi_loader/efi_bootbin.c               |   2 +-
>>>>>    lib/efi_loader/efi_bootmgr.c               |  75 +++++++++++-
>>>>>    lib/efi_loader/efi_boottime.c              |   3 +-
>>>>>    lib/efi_loader/efi_device_path.c           |  40 ++++---
>>>>>    lib/efi_loader/efi_device_path_utilities.c |   2 +-
>>>>>    lib/efi_loader/efi_fdt.c                   | 117 +++++++++++++++++++
>>>>>    lib/efi_loader/efi_helper.c                |  44 +++++++
>>>>>    12 files changed, 445 insertions(+), 136 deletions(-)
>>>>>    create mode 100644 lib/efi_loader/efi_fdt.c
>>>>>
>>>>> --
>>>>> 2.43.0
>>>>>
>>>>
>>>
>>> Can we use the best-match compatible approach as expected by the new
>>> 'make image.fit' in Linux?
>>>
>>> Filenames should be deprecated IMO. I am happy to help work on how to
>>> do that if you agree.
>>
>> Hello Simon,
>>
>> It is the OS that creates boot options. The OS can determine the exact
>> dtb file based on the compatible string and the kernel version once per
>> kernel upgrade. This is much more efficient than doing the same on every
>> boot.
>>
>> Replacing $fdtfile by a matching logic could make sense. But please
>> consider the effect on boot time if have to read through more than 1000
>> arm64 dtbs with U-Boot's non-caching file-system drivers.
> 
> The suggested option here is to use FIT, which is very fast at
> scanning the files. Please see [1]
> 
> Failing that, we could implement a way (in FIT) of specifying that the
> FDT is in an external file. In that case FIT would become a mapping
> from compatible strings to filenames.

FIT has no place in UEFI.

Best regards

Heinrich