diff options
| -rw-r--r-- | Makefile | 27 | ||||
| -rw-r--r-- | README.md | 34 |
2 files changed, 41 insertions, 20 deletions
@@ -1,5 +1,5 @@ ## -# By default everything is silent. If you want to change this behavior, simply +# By default everything is silent. If you want to change this behavior simply # assign V=1 when calling make. V = @@ -21,14 +21,19 @@ CC = $(CROSS_COMPILE)gcc$(CC_SUFFIX) LD = $(CROSS_COMPILE)ld QEMU ?= qemu-system-riscv64 -ISA ?= rv64imafdc_zicntr_zicsr_zifencei_zihpm_zca_zcd_zba_zbb -CCFLAGS = -march=$(ISA) -Iinclude/ -mabi=lp64 -CCFLAGS += -Werror -Wpedantic -Wall -Wextra -Wcast-align -Wcast-qual -Winit-self \ - -Wmissing-include-dirs -Wredundant-decls -Wshadow -Wsign-conversion \ - -Wswitch-default -Wundef -Wunreachable-code -Wmissing-noreturn -LDFLAGS = -Iinclude/ -static -nostdlib -melf64lriscv -z noexecstack -QEMU_FLAGS ?= -QEMU_BIOS ?= +ISA ?= rv64imafdc_zicntr_zicsr_zifencei_zihpm_zca_zcd_zba_zbb +CCFLAGS = -march=$(ISA) -Iinclude/ -mabi=lp64d +CCFLAGS += -Werror -Wpedantic -Wall -Wextra -Wcast-align -Wcast-qual -Winit-self \ + -Wmissing-include-dirs -Wredundant-decls -Wshadow -Wsign-conversion \ + -Wswitch-default -Wundef -Wunreachable-code -Wmissing-noreturn +LDFLAGS = -Iinclude/ -static -nostdlib -melf64lriscv -z noexecstack + +## +# Optional parameters for QEMU and gdb. + +QEMU_FLAGS ?= +QEMU_BIOS ?= +GDB_EXTRA_FLAGS ?= ## # You can pass an optional `DEBUG` variable to manipulate the build type. This @@ -74,7 +79,7 @@ $(KRNL): $(OBJ) $(LINKER).S $(Q) $(CC) $(CCFLAGS) -c $< -o $@ .PHONY: qemu -qemu: +qemu: $(KRNL) ifeq ($(strip $(QEMU_BIOS)),) $(Q) $(QEMU) $(QEMU_FLAGS) -machine virt -kernel $(KRNL) -nographic else @@ -83,7 +88,7 @@ endif .PHONY: gdb gdb: - $(Q) gdb --command utils/init.gdb + $(Q) gdb --command utils/init.gdb $(GDB_EXTRA_FLAGS) $(KRNL) .PHONY: clean clean: @@ -63,15 +63,17 @@ $ make ARCH=riscv CROSS_COMPILE=<your-cross-compile> PLATFORM=generic With that simply set the `QEMU_BIOS` environment variable with the full path of the resulting `fw_dynamic.bin` file. -Now make sure that you have the version that is able to emulate a RISC-V system. -After that, simply run: +Now make sure that you have a QEMU version that is able to emulate a RISC-V +system. After that, simply run: ``` $ make qemu ``` -The `qemu` target can be paired with the `DEBUG` parameter that you can pass to -make. Hence, you can also call it like so: +This will open up QEMU in `-nographic` mode (hence the serial output will be +simply redirected to stdout), and you will be able to see the whole thing +working. Moreover, the `qemu` target can be paired with the `DEBUG` parameter +that you can pass to make. Hence, you can also call it like so: ``` $ make qemu DEBUG=1 @@ -83,19 +85,33 @@ This will make QEMU wait for a GDB connection. On another terminal then type: $ make gdb ``` -Now you have a debugging session for this kernel. If you want to skip ahead, -notice that the kernel starts at `PAGE_OFFSET` (see `include/fbos/mm.h`). Hence, -upon starting the GDB session you can simply type: +Now you have a debugging session for this kernel with debug symbols loaded. +Hence, upon starting the GDB session you can simply type: ``` -# 0x80200000 is the current value of PAGE_OFFSET. -(gdb) break *0x80200000 +(gdb) break _start (gdb) continue ``` From there you are already out of firmware code and right into the kernel. +Moreover, you can also pass the `GDB_EXTRA_FLAGS` variable to the `make gdb` +target. This way you can pass extra parameters to gdb, such as: + +``` +$ make gdb GDB_EXTRA_FLAGS="-tui" +``` + +And now you have started a GDB session with a nice TUI interface. ## Special thanks to SUSE for organizing [Hack Week 24](https://hackweek.opensuse.org/24/projects). This project was mainly developed during this time. + +I have also taken lots of valuable input by reading [Popovic's +blog](https://popovicu.com/), so thanks a lot for writing such clear articles on +a rather obscure topic. In a similar way, I have also taken the time to read a +lot of code from the Linux Kernel. My understanding of both RISC-V and the Linux +Kernel itself has vastly improved with this exercise, so I'd also like to take +the chance to be grateful to the many people who have contributed to this vast +undertaking that is the Linux Kernel. |