kernel: add reproducible build option in Kconfig and rename final bin…

…ary name from Makefile

zeal8bit: os.bin file is now kept, and a new image containing both the OS and the romdisk is generated.

Makefile

@@ -12,6 +12,8 @@ export MENUCONFIG_STYLE = aquatic
 export OSCONFIG_ASM = include/osconfig.asm
 # Output related
 BIN=os.bin
+# As the first section of the OS  must be RST_VECTORS, the final binary is named os_RST_VECTORS.bin
+BIN_GENERATED=os_RST_VECTORS.bin
 BINDIR=build
 FULLBIN=$(BINDIR)/$(BIN)
 MAPFILE=os.map
@@ -54,7 +56,7 @@ endef
 #	- $2: Variable name where INCLUDES will be stored
 #   - $3: Variable name where PRECMD will be stored
 #   - $4: Variable name where POSTCMD will be stored
-define IMPORT_subunitmk = 
+define IMPORT_subunitmk =
     SUBMKFILE = $$(wildcard */$$(MKFILE))
     TMP1 :=
     TMP2 :=
@@ -87,15 +89,17 @@ LINKERFILE_BUILT=$(BINDIR)/$(LINKERFILE_OBJ)
 
 all:$(KCONFIG_CONFIG) version packer precmd $(LINKERFILE_OBJ) $(OBJS)
 	$(CC) -o$(FULLBIN) -b -m -s $(LINKERFILE_BUILT) $(BUILTOBJS)
+	@mv $(BINDIR)/$(BIN_GENERATED) $(FULLBIN)
 	@echo "OS binary: $(FULLBIN)"
 	@echo "Executing post commands..."
 	$(POSTCMD)
 
-    # Generate a version file that will be used as a boilerplate
-    # when the system starts
+# Generate a version file that will be used as a boilerplate when the system starts
+# We add the build time to the file only if reproducible build is not enabled
 version:
 	@echo Zeal 8-bit OS `git describe --tags` > version.txt
-	@echo Build time: `date +"%Y-%m-%d %H:%M"` >> version.txt
+	@[ -z "$(CONFIG_KERNEL_REPRODUCIBLE_BUILD)" ]  && \
+	 echo Build time: `date +"%Y-%m-%d %H:%M"` >> version.txt || true
 
 packer:
 	@echo "Building packer"
@@ -105,7 +109,7 @@ precmd:
 	@echo "Executing pre commands..."
 	@$(PRECMD)
 
-# Check if configuration file exists  
+# Check if configuration file exists
 $(KCONFIG_CONFIG):
 	@test -e $@ || { echo "Configuration file $@ could not be found. Please run make menuconfig first"; exit 1; }
 
@@ -145,10 +149,10 @@ prepare_dirs:
 	@mkdir -p $(BINDIR)
 
 dump:
-	$(DISASSEMBLER) -x $(BINDIR)/os.map $(BINDIR)/$(BIN) | less
+	$(DISASSEMBLER) -x $(BINDIR)/$(MAPFILE) $(BINDIR)/$(BIN) | less
 
 fdump:
-	$(DISASSEMBLER) -x $(BINDIR)/os.map $(BINDIR)/$(BIN) > $(BINDIR)/os.dump
+	$(DISASSEMBLER) -x $(BINDIR)/$(MAPFILE) $(BINDIR)/$(BIN) > $(BINDIR)/os.dump
 
 clean:
 	rm -rf $(OSCONFIG_ASM) $(BINDIR) $(KCONFIG_CONFIG) version.txt

kernel/Kconfig

@@ -1,13 +1,21 @@
 menu "Kernel configuration"
-
+
+        config KERNEL_REPRODUCIBLE_BUILD
+                bool "Generate a reproducible binary"
+                default n
+                help
+                        When this option is enabled, compiling the project several times with
+                        the same configuration will produce the exact same binary. Thus, information
+                        like build time will be excluded from the binary.
+
         config KERNEL_STACK_ADDR
                 hex "Kernel Stack virtual address"
                 default 0xFFFF
                 range 0x0000 0xFFFF
                 help
                         After initializing the MMU, the kernel will set the Stack Pointer (SP).
                         This value defines the top of the stack in the virtual memory.
-                        This address must point to RAM.  
+                        This address must point to RAM.
 
         config KERNEL_COLDBOOT_HOOK
                 bool "Hook routine at coldboot"
@@ -57,7 +65,7 @@ menu "Kernel configuration"
                 help
                         Maximum length of a single absolute file path. Incrementing this value will make
                         the kernel use more RAM.
-                       
+
         config KERNEL_INIT_EXECUTABLE
                 string "Executable to launch on boot"
                 default "A:/init.bin"
@@ -79,5 +87,5 @@ menu "Kernel configuration"
                 help
                         Kernel logger, by default, prints logs without any color. However, if this option
                         is enable, it will be able to print error messages in red, warning messages in yellow
-                        and info messages in green. 
+                        and info messages in green.
 endmenu

target/zeal8bit/unit.mk

@@ -2,6 +2,9 @@ INCLUDES := ./ ./include
 
 SRCS := pio.asm i2c.asm keyboard.asm romdisk.asm mmu.asm interrupt_vect.asm
 
+# Add the suffix "_romdisk" to the full binary name
+FULLBIN_W_ROMDISK = $(basename $(FULLBIN))_with_romdisk.img
+
 # If the UART is configured as the standard output, it shall be the first driver to initialize
 ifdef CONFIG_TARGET_STDOUT_UART
 	SRCS := uart.asm $(SRCS)
@@ -19,27 +22,27 @@ else
 	endif
 endif
 
-# Load the video driver first, in order to get an output early on
-
-	# Command to be executed before compiling the whole OS.
-	# In our case, compile the programs that will be part of ROMDISK and create it.
-	# After creation, get its size, thanks to `stat` command, and store it in a generated header file
-	# named `romdisk_info_h.asm`
+# Command to be executed before compiling the whole OS.
+# In our case, compile the programs that will be part of ROMDISK and create it.
+# After creation, get its size, thanks to `stat` command, and store it in a generated header file
+# named `romdisk_info_h.asm`
 PRECMD := (cd $(PWD)/romdisk && make) && \
           SIZE=$$(stat -c %s $(PWD)/romdisk/disk.img) && \
           (echo -e "IFNDEF ROMDISK_H\nDEFINE ROMDISK_H\nDEFC ROMDISK_SIZE=$$SIZE\nENDIF" > $(PWD)/include/romdisk_info_h.asm) && \
-		  unset SIZE
+          unset SIZE
 
-	# After compiling the whole OS, we need to remove the unecessary binaries:
-	# In our case, it's the binary containing BSS addresses, so we only have to keep
-	# the one containing the actual code. The filename comes from the linker's first
-	# section name: RST_VECTORS
-	# FULLBIN defines the expected final binary path/name.
-	# After selecting the rigth binary, we have to truncate it to a size that will let us
-	# easily concatenate the ROMDISK after it.
-	# Of course, the final step is to concatenate the ROMDISK to the final binary after that.
+# After compiling the whole OS, we need to remove the unnecessary binaries:
+# In our case, it's the binary containing BSS addresses, so we only have to keep
+# the one containing the actual code. The filename comes from the linker's first
+# section name: RST_VECTORS
+# FULLBIN defines the expected final binary path/name.
+# After selecting the right binary, we have to truncate it to a size that will let us
+# easily concatenate the ROMDISK after it.
+# Of course, the final step is to concatenate the ROMDISK to the final binary after that.
 POSTCMD := @echo "RAM used by kernel: $$(du -bs $(BINDIR)/*KERNEL_BSS*.bin | cut -f1) bytes" && \
-	   rm $(BINDIR)/*KERNEL_BSS*.bin && mv $(BINDIR)/*RST_VECTORS*.bin $(FULLBIN) && \
-	   echo "OS size: $$(du -bs $(FULLBIN) | cut -f1) bytes" && \
-	   truncate -s $$(( $(CONFIG_ROMDISK_ADDRESS) - $(CONFIG_KERNEL_PHYS_ADDRESS) )) $(FULLBIN) && \
-	   cat $(PWD)/romdisk/disk.img >> $(FULLBIN)
+           rm $(BINDIR)/*KERNEL_BSS*.bin && \
+           echo "OS size: $$(du -bs $(FULLBIN) | cut -f1) bytes" && \
+           cp $(FULLBIN) $(FULLBIN_W_ROMDISK) && \
+           truncate -s $$(( $(CONFIG_ROMDISK_ADDRESS) - $(CONFIG_KERNEL_PHYS_ADDRESS) )) $(FULLBIN_W_ROMDISK) && \
+           cat $(PWD)/romdisk/disk.img >> $(FULLBIN_W_ROMDISK) && \
+           echo "Image size: $$(du -bs $(FULLBIN_W_ROMDISK) | cut -f1) bytes"