On 06/25/2018 08:34 AM, Ard Biesheuvel wrote:
There are various ways a platform can provide a device tree binary
to the kernel, with different levels of sophistication:
- ideally, the UEFI firmware, which is tightly coupled with the
platform, provides a device tree image directly as a UEFI
configuration table, and typically permits the contents to be
manipulated either via menu options or via UEFI environment
variables that specify a replacement image,
- GRUB for ARM has a 'devicetree' directive which allows a device
tree image to be loaded from any location accessible to GRUB, and
supersede the one provided by the firmware,
- the EFI stub implements a dtb= command line option that allows a
device tree image to be loaded from a file residing in the same
file system as the one the kernel image was loaded from.
The dtb= command line option was never intended to be more than a
development feature, to allow the other options to be implemented
in parallel. So let's make it an opt-in feature that is disabled
by default, but can be re-enabled at will.
Note that we already disable the dtb= command line option when we
detect that we are running with UEFI Secure Boot enabled.
Signed-off-by: Ard Biesheuvel <[email protected]>
Sounds reasonable to me.
Reviewed-by: Alexander Graf <[email protected]>
Alex
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