Add build instruction

Author: vacantron

Makefile

@@ -1,6 +1,7 @@
 # TODO: check unsupported extensions
-RV32_EXT ?= rv32i
-OPT_LEVEL := 0 1 2
+
+RV32_EXT ?= rv32gc
+OPT_LEVEL ?= 0 1 2
 
 CFLAGS := -std=c99
 LDFLAGS := -lsemihost -lm

README.md

@@ -0,0 +1,46 @@
+# The test suite for [rv32emu project](https://github.com/sysprog21/rv32emu)
+
+## Prerequisites
+
+This test suite relies RISC-V GNU toolchain to build the ELF files. See the [prerequisites section](https://github.com/riscv-collab/riscv-gnu-toolchain?tab=readme-ov-file#prerequisites) of RISC-V GNU toolchain.
+
+## Build ELFs
+
+Run `make` to build the binaries.
+The default enabled extensions of RISC-V are `rv32gc` (a.k.a. rv32imafdc) and the optimization levels are `O0, O1, O2`.
+These two options can be overrided by the argument `RV32_EXT` and `OPT_LEVEL`.
+
+```shell
+$ make [RV32_EXT=<rv32_ext>] [OPT_LEVEL=<opt_level>]
+```
+
+The `RV32_EXT` takes the same value that passing to `--with-arch` of the RISC-V GNU toolchain, and the `OPT_LEVEL` takes the combination of the whitespace separated number of 0, 1, 2 and quoted with the (double) quotation marks.
+
+e.g.
+
+```shell
+$ make RV32_EXT=rv32im OPT_LEVEL="0 2"
+```
+
+Notice that the above command will build the corresponding toolchain first if it doesn't exist and might take a few time.
+You can set the `--jobs (-j)` option to enable the parallel build.
+
+---
+
+The built binaries will be placed in the corresponding subdirectories under the `build` directory.
+
+```
+rv32emu-prebuilt/
++-- build/
+|   +-- <RV32_EXT>/
+|       +-- O0/
+|       |   ...
+|       |
+|       +-- O1/
+|       |   ...
+|       |
+|       +-- O2/
+|       |   ...
+|
++-- ...
+```

src/ansibench/nbench/Makefile

@@ -7,7 +7,7 @@ SRC_DIR := $(CURDIR)/src
 CFLAGS := -c -std=c99 -I$(CURDIR)/include
 LDFLAGS := -lm
 
-# prevent lazy set if not providing initial value
+# prevent lazy set
 ifeq ($(BUILD_DIR),)
   BUILD_DIR := $(CURDIR)/build
 endif

src/asm-hello/Makefile

@@ -1,4 +1,4 @@
-RV32_EXT ?= rv32i
+RV32_EXT ?= rv32gc
 OPT_LEVEL ?= 0 1 2
 
 ASFLAGS := -march=$(RV32_EXT) -mabi=ilp32
@@ -7,7 +7,7 @@ LDFLAGS := --oformat=elf32-littleriscv
 CURDIR := $(abspath $(dir $(lastword $(MAKEFILE_LIST))))
 SRC_DIR := $(CURDIR)
 
-# prevent lazy set if not providing initial value
+# prevent lazy set
 ifeq ($(BUILD_DIR),)
   BUILD_DIR := $(CURDIR)/build
 endif