lib: utils: Improve fdt_timer

[platform/kernel/opensbi.git] / README.md

diff --git a/README.md b/README.md
index 54fabe4..a6bcb0c 100644 (file)
--- a/README.md
+++ b/README.md
@@ -92,8 +92,8 @@ N.B. Any S-mode boot loader (i.e. U-Boot) doesn't need to support HSM extension,
 as it doesn't need to boot all the harts. The operating system should be
 capable enough to bring up all other non-booting harts using HSM extension.
 
-Required Toolchain
-------------------
+Required Toolchain and Packages
+-------------------------------
 
 OpenSBI can be compiled natively or cross-compiled on a x86 host. For
 cross-compilation, you can build your own toolchain, download a prebuilt one
@@ -115,6 +115,14 @@ triple is used (e.g. *-target riscv64-unknown-elf*).
 Please note that only a 64-bit version of the toolchain is available in
 the Bootlin toolchain repository for now.
 
+In addition to a toolchain, OpenSBI also requires the following packages on
+the host:
+
+1. device-tree-compiler: The device tree compiler for compiling device
+   tree sources (DTS files).
+2. python3: The python 3.0 (or compatible) language support for various
+   scripts.
+
 Building and Installing the OpenSBI Platform-Independent Library
 ----------------------------------------------------------------
 
@@ -196,6 +204,19 @@ top-level make command line. These options, such as *PLATFORM_<xyz>* or
 *docs/platform/<platform_name>.md* files and
 *docs/firmware/<firmware_name>.md* files.
 
+All OpenSBI platforms support Kconfig style build-time configuration. Users
+can change the build-time configuration of a platform using a graphical
+interface as follows:
+```
+make PLATFORM=<platform_subdir> menuconfig
+```
+
+Alternately, an OpenSBI platform can have multiple default configurations
+and users can select a custom default configuration as follows:
+```
+make PLATFORM=<platform_subdir> PLATFORM_DEFCONFIG=<platform_custom_defconfig>
+```
+
 Building 32-bit / 64-bit OpenSBI Images
 ---------------------------------------
 By default, building OpenSBI generates 32-bit or 64-bit images based on the
@@ -277,6 +298,19 @@ NOTE: Using `BUILD_INFO=y` without specifying SOURCE_DATE_EPOCH will violate
 purpose, and should NOT be used in a product which follows "reproducible
 builds".
 
+Building with optimization off for debugging
+--------------------------------------------
+
+When debugging OpenSBI, we may want to turn off the compiler optimization and
+make debugging produce the expected results for a better debugging experience.
+To build with optimization off we can just simply add `DEBUG=1`, like:
+```
+make DEBUG=1
+```
+
+This definition is ONLY for development and debug purpose, and should NOT be
+used in a product build.
+
 Contributing to OpenSBI
 -----------------------