Hi Aswin, On Tue, 6 Jan 2026 at 14:22, Aswin Murugan <[email protected]> wrote: > > Introduce a weak function efi_load_platform_fdt() to allow platforms > to provide custom device tree selection logic. This enables platforms > with special requirements (such as multi-DTB selection based on > hardware detection) to load fdt. > > The default weak implementation does nothing, Platforms can provide > a strong implementation to load platform-specific device trees.
We have multiple methods of loading an alternative DT. You can for example define them as a boot option ion the eficonfig command. How you elaborate more on the requirements your platforms have and why the existing code isn't enough? Thanks /Ilias > > Signed-off-by: Aswin Murugan <[email protected]> > --- > include/efi_loader.h | 2 ++ > lib/efi_loader/efi_bootmgr.c | 4 ++++ > lib/efi_loader/efi_fdt.c | 23 +++++++++++++++++++++++ > 3 files changed, 29 insertions(+) > > diff --git a/include/efi_loader.h b/include/efi_loader.h > index 3e70ac07055..62c3df48f71 100644 > --- a/include/efi_loader.h > +++ b/include/efi_loader.h > @@ -1303,4 +1303,6 @@ int efi_get_distro_fdt_name(char *fname, int size, int > seq); > > void efi_load_distro_fdt(efi_handle_t handle, void **fdt, efi_uintn_t > *fdt_size); > > +void efi_load_platform_fdt(efi_handle_t handle, void **fdt, efi_uintn_t > *fdt_size); > + > #endif /* _EFI_LOADER_H */ > diff --git a/lib/efi_loader/efi_bootmgr.c b/lib/efi_loader/efi_bootmgr.c > index a687f4d8e85..ed06a65feb7 100644 > --- a/lib/efi_loader/efi_bootmgr.c > +++ b/lib/efi_loader/efi_bootmgr.c > @@ -1332,6 +1332,10 @@ efi_status_t efi_bootmgr_run(void *fdt) > efi_load_distro_fdt(handle, &fdt_distro, &fdt_size); > fdt = fdt_distro; > } > + if (!fdt) { > + efi_load_platform_fdt(handle, &fdt_distro, &fdt_size); > + fdt = fdt_distro; > + } > } > > /* > diff --git a/lib/efi_loader/efi_fdt.c b/lib/efi_loader/efi_fdt.c > index bfaa9cfc207..bfcfd933adf 100644 > --- a/lib/efi_loader/efi_fdt.c > +++ b/lib/efi_loader/efi_fdt.c > @@ -78,6 +78,29 @@ int efi_get_distro_fdt_name(char *fname, int size, int seq) > return 0; > } > > +/** > + * efi_load_platform_fdt() - Platform-specific FDT loading hook (weak) > + * > + * @handle: handle of loaded image > + * @fdt: on return device-tree, must be freed via efi_free_pages() > + * @fdt_size: buffer size > + * > + * This weak function allows platforms to provide custom DTB selection logic. > + * The default implementation does nothing, allowing the standard distro boot > + * path to handle FDT loading. Platforms can override this function to > + * implement custom multi-DTB selection or other platform-specific logic. > + * > + * If this function successfully loads a DTB, it should set *fdt to point to > + * the loaded DTB and return. If it cannot load a DTB, it should set *fdt to > + * NULL, and the standard distro boot logic will be used as fallback. > + */ > +__weak void efi_load_platform_fdt(efi_handle_t handle, void **fdt, > + efi_uintn_t *fdt_size) > +{ > + /* Default: do nothing, let standard distro boot handle it */ > + *fdt = NULL; > +} > + > /** > * efi_load_distro_fdt() - load distro device-tree > * > -- > 2.34.1 >
