[PATCH v3 0/9] efi_loader: improve device-tree loading

[Tom Rini]

On Mon, Jun 10, 2024 at 06:10:08PM +0200, Heinrich Schuchardt wrote:
> On 10.06.24 17:54, Simon Glass wrote:
> > Hi Heinrich,
> > 
> > On Mon, 10 Jun 2024 at 08:00, Heinrich Schuchardt
> > <heinrich.schuchardt at canonical.com> wrote:
> > > 
> > > On 10.06.24 15:53, Simon Glass wrote:
> > > > Hi Heinrich,
> > > > 
> > > > On Mon, 10 Jun 2024 at 03:11, 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.
> > > > > 
> > > > > v3:
> > > > >           Add missing '@' in EFI_LP_DP_PART_FDT description.
> > > > >           Use calloc() instead of malloc() in load_fdt_from_load_option().
> > > > >           Add missing '@' in load_fdt_from_load_option function description
> > > > >           Rename struct efi_initrd_dp to efi_lo_dp_prefix.
> > > > > 
> > > > > 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
> > > > > 
> > > > 
> > > > Somewhat related, what work has been done to support FIT, or to locate
> > > > a DT using the compatible string?
> > > 
> > > CONFIG_BOOTM_EFI allows booting a FIT image containing an EFI binary and
> > > optionally a device-tree. You can manually select a configuration when
> > > invoking the bootm command. I am not aware of any automation for this
> > > selection.
> > 
> > Thanks for the info.
> > 
> > Can we perhaps require FIT_BEST_MATCH and then provide a way? All this
> > filename stuff is missing the point, really. It isn't going to get any
> > easier, either.
> > 
> 
> Thanks for the pointer. FIT_BEST_MATCH would allow to select a matching
> device-tree from a FIT image. But any solution using FIT images will not not
> be compatible to other firmware.
> 
> As a distro I would prefer a solution that runs on any EFI firmware, e.g.
> EDK II. Being able to use the same image on all boards of the same
> architecture was the motivator for Suse to start U-Boot's EFI
> implementation.

I'm pretty sure tianocore, grub and systemd takes patches too? And
everyone is going to need to do _something_ because all of the measured
boot stuff that distributions want starts from "we can't check the
measurement of 10000 files, we need to check one file". So it's pretty
handy then that there's an open and well known specification that
handles that problem. I'm still frankly a little baffled as to what
would prevent UKI from being "EFI application stub around a FIT image".

-- 
Tom
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