efi_stub: update documentation on dtb= parameter (9331e5e7) · Commits · 戴 / test

The dtb= parameter is no longer the primary mechanism for providing a devicetree to the kernel. Now either firmware or the boot selector (ex. Grub) should provide the devicetree and dtb= should only be used for debug or when using firmware that doesn't understand DT. Update the EFI stub documentation to reflect the current usage. Signed-off-by:

Grant Likely <grant.likely@arm.com> Reviewed-by:

Alexander Graf <agraf@suse.de> Acked-by:

Leif Lindholm <leif.lindholm@linaro.org> Acked-by:

Olof Johansson <olof@lixom.net> Acked-by:

Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by:

Jonathan Corbet <corbet@lwn.net>

Documentation/efi-stub.txt

+14 −3

Original line number	Diff line number	Diff line
		@@ -83,7 +83,18 @@ is passed to bzImage.efi.
		The "dtb=" option
		-----------------

		For the ARM and arm64 architectures, we also need to be able to provide a
		device tree to the kernel. This is done with the "dtb=" command line option,
		and is processed in the same manner as the "initrd=" option that is
		For the ARM and arm64 architectures, a device tree must be provided to
		the kernel. Normally firmware shall supply the device tree via the
		EFI CONFIGURATION TABLE. However, the "dtb=" command line option can
		be used to override the firmware supplied device tree, or to supply
		one when firmware is unable to.

		Please note: Firmware adds runtime configuration information to the
		device tree before booting the kernel. If dtb= is used to override
		the device tree, then any runtime data provided by firmware will be
		lost. The dtb= option should only be used either as a debug tool, or
		as a last resort when a device tree is not provided in the EFI
		CONFIGURATION TABLE.

		"dtb=" is processed in the same manner as the "initrd=" option that is
		described above.

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