Moved kernel build out of world and into kernel subdir

Target for kernel build is once again buildkernel

kernel/Makefile

@@ -0,0 +1,77 @@
+#  Makefile - hhl - /usr/src/world/linux-mainline
+#  Copyright 2020 Nathan Fisher <nfisher.sr@gmail.com>
+#
+distname     = linux
+default_goal = installkernel
+include world.mk
+srcdir       = $(basedir)/build/src-world-$(arch)/linux-$(linux_version)
+objdir       = $(basedir)/build/obj-world-$(arch)/linux-$(linux_version)
+
+config      ?= $(wkgdir)/config-$(arch)-$(linux_version).config
+
+ifeq ($(filter x86_64 i486 i586 i686 i786, $(arch)), $(arch))
+ _arch       = x86
+ image       = bzImage
+else ifeq ($(arch), armv7l)
+ _arch       = arm
+ image       = zImage
+else
+ image       = Image.gz
+endif
+ifeq ($(arch), aarch64)
+ _arch       = arm64
+else ifeq ($(arch), riscv64)
+ _arch       = riscv
+endif
+
+installkernel: $(objdir)/.installed
+
+buildkernel: $(objdir)/.built
+
+$(objdir)/.mrproper: $(srcdir)/.dirstamp | $(objdir)
+	$(MAKE) -C ${srcdir} mrproper
+	touch $@
+
+$(objdir)/.config: $(objdir)/.mrproper
+	$(info $(grn)=== Applying default kernel config ===$(reset))
+	cat ${config} > $(objdir)/.config
+	KBUILD_OUTPUT=$(objdir) $(MAKE) -C $(srcdir) ARCH=$(_arch) CROSS_COMPILE=$(tgt)- olddefconfig
+
+menuconfig: $(objdir)/.mrproper
+	$(info $(grn)=== Applying default kernel config ===$(reset))
+	cat ${config} > $(objdir)/.config
+	KBUILD_OUTPUT=$(objdir) $(MAKE) -C $(srcdir) ARCH=$(_arch) CROSS_COMPILE=$(tgt)- olddefconfig
+	KBUILD_OUTPUT=$(objdir) $(MAKE) -C $(srcdir) ARCH=$(_arch) CROSS_COMPILE=$(tgt)- menuconfig
+
+$(objdir)/.built: $(objdir)/.config
+	$(info $(grn)=== Building Linux kernel ===$(reset))
+	KBUILD_OUTPUT=$(objdir) $(MAKE) $(makeflags) ARCH=$(_arch) CROSS_COMPILE=$(tgt)- -C $(srcdir)
+	touch $@
+
+$(objdir)/.modules_installed: $(objdir)/.built
+	$(info $(grn)=== Installing kernel modules ===$(reset))
+	KBUILD_OUTPUT=$(objdir) INSTALL_MOD_PATH=$(DESTDIR) $(MAKE) -C $(srcdir) modules_install
+	touch $@
+
+$(objdir)/.docs_installed: $(objdir)/.built
+	$(info $(grn)=== Installing kernel documentation ===$(reset))
+	install -d $(docdir)/linux-$(linux_version)
+	cp -r $(srcdir)/Documentation/* $(docdir)/linux-$(linux_version)
+	touch $@
+
+$(objdir)/.installed: $(objdir)/.modules_installed $(objdir)/.docs_installed
+	$(info $(grn)=== Installing kernel ===$(reset))
+	install -m644 $(objdir)/arch/$(_arch)/boot/$(image) $(DESTDIR)/boot/vmlinuz-$(linux_version)-$(os_abbrev)-$(os_version)
+	install -m644 $(objdir)/System.map $(DESTDIR)/boot/System.map-$(linux_version)
+	install -m644 $(objdir)/.config $(DESTDIR)/boot/config-$(linux_version)
+	touch $@
+
+$(objdir):
+	install -d ${objdir}
+
+$(srcdir)/.dirstamp:
+	$(info $(grn)=== Extracting $(distlocal) ===$(reset))
+	tar -xf $(distlocal) -C $(basedir)/build/src-world
+	touch $@
+
+.PHONY: buildkernel installkernel