Handout

tools/image.mk

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+# Generates a bootable ISO image that can be transferred to external media, such as CDs or USB sticks.
+# This will install, in addition to your kernel, the bootloader GRUB (https://www.gnu.org/software/grub/).
+#
+# The target 'gemu-iso' is used to test the image generated with 'iso'.
+#
+# Assuming that a USB mass-storage devices is connected as, for instance /dev/sdc, the target 'usb-sdc'
+# can be used to make your device bootable (requires root access, substitute sdc with the matching device).
+# Alternatively, you can burn the .iso file directly to CD.
+
+DD = dd
+XORRISO = xorriso
+MKISO = grub-mkrescue
+
+ISODIR = $(BUILDDIR)-iso
+ISOGRUBCFG = boot/grub/grub.cfg
+ISOKERNEL = boot/kernel
+ISOINITRD = initrd
+GRUBTITLE = $(shell id -un)s $(PROJECT)
+GRUBTIMEOUT = 2
+GRUBBIN = /usr/lib/grub/i386-pc
+
+# Default ISO target
+iso: $(ISOFILE)
+
+# Create Grub config
+$(ISODIR)/$(ISOGRUBCFG):
+	@echo "GEN		$@"
+	@mkdir -p $(dir $@)
+	@$(echo) "set timeout=$(GRUBTIMEOUT)\nset default=0\n\nmenuentry \"$(GRUBTITLE)\" {\n\tmultiboot /$(ISOKERNEL)\n\tmodule /$(ISOINITRD)\n\tboot\n}" > $@
+
+# Strip debug symbols from kernel binary
+$(ISODIR)/$(ISOKERNEL): all
+	@echo "STRIP		$@"
+	@mkdir -p $(dir $@)
+	$(VERBOSE) $(STRIP) --strip-debug --strip-unneeded -p -o $@ $(KERNEL)
+
+# copy inital ramdisk
+$(ISODIR)/$(ISOINITRD): all
+	@echo "CPY		$@"
+	@mkdir -p $(dir $@)
+	@if [ -s $(INITRD) ] ; then cp -a $(INITRD) $@ ; else touch $@ ; fi
+
+# Pack to ISO
+$(ISOFILE): $(ISODIR)/$(ISOKERNEL) $(ISODIR)/$(ISOINITRD) $(ISODIR)/$(ISOGRUBCFG)
+	@echo "ISO		$@"
+	@which $(XORRISO) >/dev/null || echo "Xorriso cannot be found - if building the ISO fails, this may be the reason!" >&2
+	$(VERBOSE) $(MKISO) -d $(GRUBBIN) -o $@ $(ISODIR)
+
+# Run ISO in QEMU/KVM
+%-iso: $(ISOFILE)
+	@${MAKE} -s QEMUKERNEL="-cdrom $<" $*
+
+# Copy ISO to USB device
+usb: $(ISOFILE)
+ifeq (,$(USBDEV))
+	@echo "The environment variable USBDEV must contain the path to the USB mass-storage device:" >&2
+	@lsblk -o TYPE,KNAME,SIZE,MODEL -a -p | grep "^disk" | cut -b 6-
+	@exit 1
+else
+	$(VERBOSE) $(DD) if=$< of=$(USBDEV) bs=4M status=progress && sync
+endif
+
+# Shorthand to copy ISO to a specific USB device
+usb-%:
+	@$(MAKE) USBDEV=/dev/$* usb
+
+# Burn ISO to CD
+cd: $(ISOFILE)
+ifeq (,$(CDRWDEV))
+	@echo "The environment variable CDRWDEV must contain the path to the CD/DVD writer" >&2
+	@exit 1
+else
+	$(VERBOSE) $(XORRISO) -as cdrecord -v dev=$(CDRWDEV) -dao $<
+endif
+
+# Shorthand to nurn ISO to specific CD device
+cd-%:
+	@$(MAKE) CDRWDEV=/dev/$* cd
+
+# The standard target 'clean' removes the whole generated system, the object files, and the dependency files.
+clean::
+	@echo "RM		$(ISODIR)"
+	$(VERBOSE) rm -rf "$(ISODIR)" "$(ISODIR)$(OPTTAG)" "$(ISODIR)$(NOOPTTAG)" "$(ISODIR)$(DBGTAG)" "$(ISODIR)$(VERBOSETAG)"
+
+# Documentation
+help::
+	@$(echo) "Bootable Images\n" \
+		"	\e[3miso\e[0m      Generates a bootable system image (File: $(ISOFILE))\n\n" \
+		"	\e[3m*-iso\e[0m    Simulate the system by booting from the virtual CD drive. (e.g. qemu-iso)\n\n" \
+		"	\e[3musb\e[0m      Generates a bootable USB mass-storage device; the environment\n" \
+		"	         variable \e[4mUSBDEV\e[0m should point to the USB device\n\n" \
+		"	\e[3mcd\e[0m       Generates a bootable CD; the environment variable \e[4mCDRWDEV\e[0m\n" \
+		"	         should point to the CD writer\n\n"
+
+# Phony targets
+.PHONY: iso cd usb help