This patch provides documentation of the [U]EFI runtime service and
configuration features for the arm architecture.
Changes since v1/v2:
- Complete rewrite.
- New FDT bindings.
Cc: Rob Landley <r...@landley.net>
Cc: linux-...@vger.kernel.org
Signed-off-by: Leif Lindholm <leif.lindh...@linaro.org>
---
Documentation/arm/00-INDEX | 3 +++
Documentation/arm/uefi.txt | 61 ++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 64 insertions(+)
create mode 100644 Documentation/arm/uefi.txt
diff --git a/Documentation/arm/00-INDEX b/Documentation/arm/00-INDEX
index 36420e1..b3af704 100644
--- a/Documentation/arm/00-INDEX
+++ b/Documentation/arm/00-INDEX
@@ -34,3 +34,6 @@ nwfpe/
- NWFPE floating point emulator documentation
swp_emulation
- SWP/SWPB emulation handler/logging description
+
+uefi.txt
+ - [U]EFI configuration and runtime services documentation
diff --git a/Documentation/arm/uefi.txt b/Documentation/arm/uefi.txt
new file mode 100644
index 0000000..9ba59509
--- /dev/null
+++ b/Documentation/arm/uefi.txt
@@ -0,0 +1,61 @@
+UEFI, the Unified Extensible Firmware Interface is, a specification
+governing the behaviours of compatible firmware interfaces. It is
+maintained by the UEFI Forum - http://www.uefi.org/.
+
+UEFI is an evolution of its predecessor 'EFI', so the terms EFI and
+UEFI are used somewhat interchangeably in this document and associated
+source code. As a rule, anything new uses 'UEFI', whereas 'EFI' refers
+to legacy code or specifications.
+
+UEFI support in Linux
+=====================
+Booting on a platform with firmware compliant with the UEFI specification
+makes it possible for the kernel to support additional features:
+- UEFI Runtime Services
+- Retrieving various configuration information through the standardised
+ interface of UEFI configuration tables. (ACPI, SMBIOS, ...)
+
+For actually enabling [U]EFI support, enable:
+- CONFIG_EFI=y
+- CONFIG_EFI_VARS=y or m
+
+The implementation depends on receiving information about the UEFI environment
+in a Flattened Device Tree (FDT) - so is only available with CONFIG_OF.
+
+UEFI stub
+=========
+The "stub" is a feature that turns the Image/zImage into a valid UEFI PE/COFF
+executable, including a loader application that makes it possible to load the
+kernel directly from the UEFI shell, boot menu, or one of the lightweight
+bootloaders like Gummiboot or rEFInd.
+
+The kernel image built with stub support remains a valid kernel image for
+booting in non-UEFI environments.
+
+UEFI kernel support on ARM
+==========================
+UEFI kernel support on the ARM architectures (arm and arm64) is only available
+when boot is performed through the stub.
+
+The stub populates the FDT /chosen node with (and the kernel scans for) the
+following parameters:
+________________________________________________________________________________
+Name | Size | Description
+================================================================================
+linux,uefi-system-table | 64-bit | Physical address of the UEFI System Table.
+--------------------------------------------------------------------------------
+linux,uefi-mmap-start | 64-bit | Physical address of the UEFI memory map,
+ | | populated by the UEFI GetMemoryMap() call.
+--------------------------------------------------------------------------------
+linux,uefi-mmap-size | 32-bit | Size in bytes of the UEFI memory map
+ | | pointed to in previous entry.
+--------------------------------------------------------------------------------
+linux,uefi-mmap-desc-size | 32-bit | Size in bytes of each entry in the UEFI
+ | | memory map.
+--------------------------------------------------------------------------------
+linux,uefi-mmap-desc-ver | 32-bit | Version of the mmap descriptor format.
+--------------------------------------------------------------------------------
+linux,uefi-stub-kern-ver | string | Copy of linux_banner from build.
+--------------------------------------------------------------------------------
+
+For verbose debug messages, specify 'uefi_debug' on the kernel command line.
--
1.7.10.4
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
