5 files changed, 66 insertions, 41 deletions
diff --git a/docs/firmware/fw_payload.md b/docs/firmware/fw_payload.md
index 2fab092..0e705a2 100644
--- a/docs/firmware/fw_payload.md
+++ b/docs/firmware/fw_payload.md
@@ -1,51 +1,66 @@
 OpenSBI Firmware with Payload (FW_PAYLOAD)
 ==========================================
 
-The **OpenSBI firmware with Payload (FW_PAYLOAD)** is a
-firmware which includes next booting stage binary (i.e.
-bootloader/kernel) as payload in the OpenSBI firmware binary.
+The **OpenSBI firmware with Payload (FW_PAYLOAD)** is a firmware which
+includes the next booting stage binary (i.e. bootloader/kernel) as a
+payload embedded in the OpenSBI firmware binary image.
 
-This **FW_PAYLOAD** firmware is particularly useful when
-booting stage prior to OpenSBI firmware is not capable of
-loading OpenSBI firmware and booting stage after OpenSBI
-firmware separately.
+This *FW_PAYLOAD* firmware is particularly useful when the booting stage
+prior to OpenSBI firmware is not capable of loading the OpenSBI firmware
+and the booting stage after OpenSBI firmware separately.
 
-It is also possible that booting stage prior to OpenSBI
-firmware does not pass **flattened device tree (FDT)**. In
-this case, we have provision to embed FDT in .text section
-of **FW_PAYLOAD** firmware.
+It is also possible that the booting stage prior to OpenSBI firmware
+does not pass a *flattened device tree (FDT)*. In this case, a
+*FW_PAYLOAD* firmware allows embedding a flattened device tree in
+the .text section of the final firmware.
 
 How to Enable?
 --------------
 
-The **FW_PAYLOAD** firmware can be enabled by any of the
-following methods:
+The *FW_PAYLOAD* firmware can be enabled by any of the following methods:
 
-1. Passing `FW_PAYLOAD=y` command-line parameter to
-top-level `make`
+1. Passing `FW_PAYLOAD=y` command-line parameter to top-level `make`
 2. Setting `FW_PAYLOAD=y` in platform `config.mk`
 
-Config Options
---------------
+Configuration Options
+---------------------
+
+A *FW_PAYLOAD* firmware needs to be built according to some predefined
+configuation options to work correctly. These configuration details can
+be passed as paramters to the top-level `make` command or can be defined
+ in a platform *config.mk* build configuration file.
+
+The following are the build configuration parameters for a *FW_PAYLOAD*
+firmware:
+
+* **FW_PAYLOAD_OFFSET** - Offset from *FW_TEXT_BASE* where the payload
+binary will be linked in the final *FW_PAYLOAD* firmware binary image.
+This configuration parameter is mandatory if *FW_PAYLOAD_ALIGN* is not
+defined.  Compilation errors will result from an incorrect definition
+of *FW_PAYLOAD_OFFSET* or *FW_PAYLOAD_ALIGN*, or if neither of these
+paramreters are defined.
+
+* **FW_PAYLOAD_ALIGN** - Address alignment constraint where the payload
+binary will be linked after the end of the base firmaware binary in the
+final *FW_PAYLOAD* firmware binary image. This configuration parameter
+is mandatory if *FW_PAYLOAD_OFFSET* is not defined and should not be
+defined otherwise.
+
+* **FW_PAYLOAD_PATH** - Path to the next booting stage binary image
+file.  If this option is not provided then a simple test payload is
+automatically generated, executing a `while (1)` loop.
+
+* **FW_PAYLOAD_FDT_PATH** - Path to an external flattened device tree
+binary file to be embedded in the *.text* section of the final
+*FW_PAYLOAD* firmware. If this option is not provided and no internal
+device tree file is specified by the platform (c.f. *FW_PAYLOAD_FDT*),
+then the firmware will expect the FDT to be passed as an argument by
+the prior booting stage.
+
+* **FW_PAYLOAD_FDT_ADDR** - Address where the FDT passed by the prior
+booting stage or specified by the *FW_PAYLOAD_FDT_PATH* parameter and
+embedded in the *.text* section will be placed before executing the
+next booting stage, that is, the payload firmware. If this option is
+not provided then the firmware will pass zero as the FDT address to the
+next booting stage.
 
-We need more config details for **FW_PAYLOAD** firmware to
-work correctly. These config details can be passed as paramter
-to top-level `make` or can be set in platform `config.mk`.
-
-Following are the config options for **FW_PAYLOAD** firmware:
-
-* **FW_PAYLOAD_OFFSET** - Offset from FW_TEXT_BASE where next
-booting stage binary will be linked to **FW_PAYLOAD** firmware.
-This is a mandatory config option and will result in compile
-error if not provided.
-* **FW_PAYLOAD_PATH** - Path to the next booting stage binary.
-If this option is not provided then **`while (1)`** is taken as
-payload.
-* **FW_PAYLOAD_FDT_PATH** - Path to the FDT binary to be embedded
-in .text section of **FW_PAYLOAD** firmware. If this option is
-not provided then firmware will expect FDT to be passed by prior
-booting stage.
-* **FW_PAYLOAD_FDT_ADDR** - Address where FDT passed by prior
-booting stage (or embedded FDT) will be placed before passing
-to next booting stage. If this option is not provided then
-firmware will pass zero as FDT address to next booting stage.
-\ No newline at end of file
diff --git a/firmware/fw_payload.elf.ldS b/firmware/fw_payload.elf.ldS
index 0713f43..7106005 100644
--- a/firmware/fw_payload.elf.ldS
+++ b/firmware/fw_payload.elf.ldS
@@ -14,7 +14,11 @@ SECTIONS
 {
 	#include "fw_base.ldS"
 
+#ifdef FW_PAYLOAD_OFFSET
 	. = FW_TEXT_START + FW_PAYLOAD_OFFSET;
+#else
+	. = ALIGN(FW_PAYLOAD_ALIGN);
+#endif
 
 	.payload :
 	{
diff --git a/firmware/objects.mk b/firmware/objects.mk
index 18a1fbc..b579ba6 100644
--- a/firmware/objects.mk
+++ b/firmware/objects.mk
@@ -35,6 +35,10 @@ firmware-genflags-$(FW_PAYLOAD) += -DFW_PAYLOAD_PATH=$(FW_PAYLOAD_PATH_FINAL)
 ifdef FW_PAYLOAD_OFFSET
 firmware-genflags-$(FW_PAYLOAD) += -DFW_PAYLOAD_OFFSET=$(FW_PAYLOAD_OFFSET)
 endif
+ifdef FW_PAYLOAD_ALIGN
+firmware-genflags-$(FW_PAYLOAD) += -DFW_PAYLOAD_ALIGN=$(FW_PAYLOAD_ALIGN)
+endif
+
 ifdef FW_PAYLOAD_FDT_PATH
 firmware-genflags-$(FW_PAYLOAD) += -DFW_PAYLOAD_FDT_PATH=$(FW_PAYLOAD_FDT_PATH)
 endif
diff --git a/firmware/payloads/dummy.elf.ldS b/firmware/payloads/dummy.elf.ldS
index b4d9f75..d0854d5 100644
--- a/firmware/payloads/dummy.elf.ldS
+++ b/firmware/payloads/dummy.elf.ldS
@@ -12,7 +12,11 @@ ENTRY(_start)
 
 SECTIONS
 {
+#ifdef FW_PAYLOAD_OFFSET
 	. = FW_TEXT_START + FW_PAYLOAD_OFFSET;
+#else
+	. = ALIGN(FW_PAYLOAD_ALIGN);
+#endif
 
 	PROVIDE(_payload_start = .);
 
diff --git a/platform/kendryte/k210/config.mk b/platform/kendryte/k210/config.mk
index b8510cb..eed8bfb 100644
--- a/platform/kendryte/k210/config.mk
+++ b/platform/kendryte/k210/config.mk
@@ -19,10 +19,8 @@ PLATFORM_SYS_CLINT=y
 
 # Blobs to build
 FW_TEXT_START=0x80000000
-FW_JUMP=n
 FW_PAYLOAD=y
-FW_PAYLOAD_OFFSET=0x10000
-#FW_PAYLOAD_FDT_ADDR=0x80040000
+FW_PAYLOAD_ALIGN=0x1000
 
 # External Libraries to include
 PLATFORM_INCLUDE_LIBC=y