Simplify specifying packages to build/install

The Portage packages that need to be built and/or installed are now
specified in the `build.packages` and `install.packages` files,
respectively.  Similarly, packages to be installed on the host system
are specified in `host-tools.packages`.  Finally, the
`installonly.packages` file contains a list of packages that are
installed in the destination root, but not built in the sysroot
beforehand.

This allows `make` to better track when the package sets change.  It
will also make it easier to maintain different sets for different
variants in the future.

Makefile

@@ -19,6 +19,7 @@ prepare: $(O)/.prepared
 
 $(O)/.host-tools: \
 		build-host-tools.sh \
+		host-tools.packages \
 		$(O)/.prepared
 	./build-host-tools.sh
 	touch $(O)/.host-tools
@@ -27,18 +28,27 @@ host-tools: $(O)/.host-tools
 
 $(O)/.built: \
 		build.sh \
-		build-rootfs.sh \
-		$(O)/linux/arch/arm64/boot/Image.gz \
+		build.packages \
+		install.packages \
 		$(O)/.host-tools \
 		$(O)/.prepared
 	./build.sh
-	./build-rootfs.sh
 	touch $(O)/.built
 
+$(O)/.ready: \
+		build-rootfs.sh \
+		install.packages \
+		installonly.packages \
+		$(O)/linux/arch/arm64/boot/Image.gz \
+		$(O)/.host-tools \
+		$(O)/.built
+	./build-rootfs.sh
+	touch $(O)/.ready
+
 $(IMAGESDIR)/rootfs.squashfs: \
 		build-squashfs.sh \
 		squashfs.exclude \
-		$(O)/.built
+		$(O)/.ready
 	./build-squashfs.sh "$(IMAGESDIR)"
 
 squashfs: $(IMAGESDIR)/rootfs.squashfs

build-host-tools.sh

@@ -1,12 +1,5 @@
 #!/bin/sh
 # vim: set sw=4 ts=4 sts=4 et :
 
-emerge -vnUj \
-    sys-apps/systemd \
-    sys-boot/grub \
-    sys-fs/btrfs-progs \
-    sys-fs/dosfstools \
-    sys-fs/genimage \
-    sys-fs/mtools \
-    sys-fs/squashfs-tools \
-    || exit
+< host-tools.packages xargs -ro \
+emerge -vnUj

build-rootfs.sh

@@ -24,19 +24,13 @@ cp -r portage/. /mnt/gentoo/etc/portage/
 
 ROOT=/mnt/gentoo \
 PORTAGE_CONFIGROOT=/mnt/gentoo \
-${target}-emerge -Kvnj \
-    sys-apps/busybox \
-    sys-apps/systemd \
-    net-misc/openssh \
-    net-misc/wget \
-    sys-fs/btrfs-progs \
-    --
+< install.packages xargs -ro \
+${target}-emerge -Kvnj
+
 ROOT=/mnt/gentoo \
 PORTAGE_CONFIGROOT=/mnt/gentoo \
-${target}-emerge -vnj \
-    net-wireless/wireless-regdb \
-    sys-kernel/linux-firmware \
-    --
+< installonly.packages xargs -ro \
+${target}-emerge -vnj
 
 ROOT=/mnt/gentoo \
 locale-gen

build.packages

@@ -0,0 +1,2 @@
+sys-boot/grub
+sys-boot/raspberrypi-firmware

build.sh

@@ -9,13 +9,9 @@ unset MAKEFLAGS MAKEOVERRIDES MAKELEVEL
 
 ${target}-emerge -vuUDj sys-apps/util-linux
 
-${target}-emerge -vnuUDj \
-    net-misc/openssh \
-    net-misc/wget \
-    sys-apps/busybox \
-    sys-apps/systemd \
-    sys-boot/grub \
-    sys-boot/raspberrypi-firmware \
-    sys-fs/btrfs-progs \
-    --
+cat \
+    build.packages \
+    install.packages \
+    | xargs -ro \
+${target}-emerge -vnuUDj
 ${target}-emerge -v @preserved-rebuild

host-tools.packages

@@ -0,0 +1,7 @@
+sys-apps/systemd
+sys-boot/grub
+sys-fs/btrfs-progs
+sys-fs/dosfstools
+sys-fs/genimage
+sys-fs/mtools
+sys-fs/squashfs-tools

install.packages

@@ -0,0 +1,5 @@
+net-misc/openssh
+net-misc/wget
+sys-apps/busybox
+sys-apps/systemd
+sys-fs/btrfs-progs

installonly.packages

@@ -0,0 +1,2 @@
+net-wireless/wireless-regdb
+sys-kernel/linux-firmware