gemini: Add swap partition to DNS-313

Sometimes when using the DNS-313 memory usage can peak and
with a simple swap partition we can avoid running into the
roof and invoking the OOM killer. Set this partition to
128MB (twice the size of the memory of the DNS-313).

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

target/linux/gemini/image/dns313_gen_hdd_img.sh

@@ -15,14 +15,20 @@ ROOTFSSIZE="$5"
 head=4
 sect=63
 
-# Create two empty partitions followed by the boot partition with
-# the ./boot/zImage and then the rootfs partition.
-set $(ptgen -o $OUTPUT -h $head -s $sect -t 83 -n -p 0 -p 0 -p ${BOOTFSSIZE}M -p ${ROOTFSSIZE}M)
+# Create one empty partitions followed by the swap partition, then the
+# boot partition with the ./boot/zImage and then the rootfs partition.
+# The swap partition with type 82 is 128 MB since the DNS-313 has 64 MB of
+# memory so we assign twice of that as swap.
+# The boot partition must always be the third partition.
+# The user should use the first (blank) partition for user data storage,
+# this will typically be named /dev/sda1
+set $(ptgen -o $OUTPUT -h $head -s $sect -n -t 83 -p 0 -t 82 -p 128M -t 83 -p ${BOOTFSSIZE}M -t 83 -p ${ROOTFSSIZE}M)
 
-BOOTOFFSET="$(($1 / 512))"
-BOOTSIZE="$(($2 / 512))"
-ROOTFSOFFSET="$(($3 / 512))"
-ROOTFSSIZE="$(($4 / 512))"
+# Swapoffset and swapsize will be $1 and $2
+BOOTOFFSET="$(($3 / 512))"
+BOOTSIZE="$(($4 / 512))"
+ROOTFSOFFSET="$(($5 / 512))"
+ROOTFSSIZE="$(($6 / 512))"
 
 dd bs=512 if="$BOOTFS" of="$OUTPUT" seek="$BOOTOFFSET" conv=notrunc
 dd bs=512 if="$ROOTFS" of="$OUTPUT" seek="$ROOTFSOFFSET" conv=notrunc