Enable APT cache / describe how to debootstrap

.gitignore

@@ -1,2 +1,4 @@
 env
 debian
+cache/*
+!cache/.gitkeep

Makefile

@@ -78,7 +78,13 @@ debian:
 		exit 1; \
 	fi
 	mkdir debian
-	sudo debootstrap --arch=armel --foreign buster debian/
+	sudo debootstrap --arch=armel --foreign buster debian/ http://localhost:65432/debian/
 	sudo cp /usr/bin/qemu-arm-static debian/usr/bin/
 	sudo cp ./tools/setup_debian.sh debian/
 	sudo chroot debian /setup_debian.sh
+
+.PHONY:
+aptcache:
+	./tools/aptcache_linux_amd64 \
+		-rule 'local=localhost:65432, remote=ftp.jaist.ac.jp' \
+		-rule 'local=localhost:65433, remote=security.debian.org'

README.md

@@ -75,6 +75,24 @@ Build Linux
 1. Confirm that `linux-brain/arch/arm/boot/zImage` exists.
 
 
+Bootstrap Debian Buster
+-----------------------
+
+1. Partition an SD card into two partitions
+
+    - 1st: FAT32 (vfat), about 100MB
+    - 2st: ext4, fill remaining capacity
+
+1. Run APT cache in background: `make aptcache`
+
+1. Run `make debian`
+
+1. Copy all contents in `./debian` into the 2nd partition in the card.
+
+    - `sudo cp -ar ./debian/* /path/to/your/sd/2nd/partition/`
+    - Please make sure that all attributes are preserved with `-a` flag
+
+
 Watch changes in submodules & auto-build
 ----------------------------------------