Re: [PATCH 03/22] efi: add helper function to get UEFI params from FDT

From: Mark Salter
Date: Thu Feb 13 2014 - 09:56:53 EST


On Thu, 2014-02-13 at 11:17 +0000, Matt Fleming wrote:
> On Wed, 05 Feb, at 05:03:54PM, Leif Lindholm wrote:
> > From: Mark Salter <msalter@xxxxxxxxxx>
> >
> > ARM and ARM64 architectures use the device tree to pass UEFI parameters
> > from stub to kernel. These parameters are things known to the stub but
> > not discoverable by the kernel after the stub calls ExitBootSerives().
> > There is a helper function in:
> >
> > drivers/firmware/efi/fdt.c
> >
> > which the stub uses to add the UEFI parameters to the device tree.
> > This patch adds a complimentary helper function which UEFI runtime
> > support may use to retrieve the parameters from the device tree.
> > If an architecture wants to use this helper, it should select
> > CONFIG_UEFI_PARAMS_FROM_FDT.
> >
> > Signed-off-by: Mark Salter <msalter@xxxxxxxxxx>
> > Signed-off-by: Leif Lindholm <leif.lindholm@xxxxxxxxxx>
> > ---
> > drivers/firmware/efi/Kconfig | 7 ++++
> > drivers/firmware/efi/efi.c | 79 ++++++++++++++++++++++++++++++++++++++++++
> > include/linux/efi.h | 9 +++++
> > 3 files changed, 95 insertions(+)
>
> Is there a particular reason this change is being added to
> drivers/firmware/efi/efi.c and not drivers/firmware/efi/fdt.c?
>

drivers/firmware/efi/fdt.c is included by the stub which may or may not
be linked into kernel image. This helper is used by runtime services and
needs to be built into kernel.

--Mark


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