rpi-zram-service: Add little systemd service to enable zram on the RPi.

* Needs to move to something more generic in time.

3 files changed, 78 insertions, 0 deletions

diff --git a/recipes-core/systemd/rpi-zram-service.bb b/recipes-core/systemd/rpi-zram-service.bb
new file mode 100644
index 0000000..f9e1e9c
--- /dev/null
+++ b/recipes-core/systemd/rpi-zram-service.bb
@@ -0,0 +1,30 @@
+DESCRIPTION = "Linux zram compressed in-memory swap systemd service"
+LICENSE = "MIT"
+LIC_FILES_CHKSUM = "file://${COREBASE}/LICENSE;md5=3f40d7994397109285ec7b81fdeb3b58"
+
+inherit allarch systemd
+
+PR = "r0"
+
+SRC_URI = "file://rpi-zram.service \
+           file://rpi-load-zram.sh \
+          "
+
+do_compile() {
+    :
+}
+
+
+do_install () {
+        install -d ${D}/${bindir}
+
+        install -m 0755 ${WORKDIR}/rpi-load-zram.sh ${D}/${bindir}
+        
+        install -d ${D}/${base_libdir}/systemd/system
+        install -m 0644 ${WORKDIR}/rpi-zram.service ${D}/${base_libdir}/systemd/system/
+}
+
+SYSTEMD_PACKAGES = "${PN}"
+SYSTEMD_SERVICE_${PN} = "rpi-zram.service"
+
+FILES_${PN} += "${base_libdir}/systemd"
diff --git a/recipes-core/systemd/rpi-zram-service/rpi-load-zram.sh b/recipes-core/systemd/rpi-zram-service/rpi-load-zram.sh
new file mode 100644
index 0000000..984dcd1
--- /dev/null
+++ b/recipes-core/systemd/rpi-zram-service/rpi-load-zram.sh
@@ -0,0 +1,36 @@
+#!/bin/sh
+
+num_cpus=$(grep -c processor /proc/cpuinfo)
+[ "$num_cpus" != 0 ] || num_cpus=1
+
+last_cpu=$((num_cpus - 1))
+
+mem_by_cpu=$(awk -v cpus=$num_cpus '/MemTotal/ { print (($2 * 1024) / cpus) }' /proc/meminfo)
+
+if [ "$1" = "--load" ] ; then
+        echo zram: Trying to load kernel module.
+        
+        # Linux 3.2 workaround - value name changed :o.
+        # modprobe -q zram zram_num_devices=$num_cpus
+        
+        # Linux < 3.2.
+        modprobe -q zram num_devices=$num_cpus 
+
+        echo zram: Enable in-memory compressed swap of $mem_by_cpu bytes.
+        for i in $(seq 0 $last_cpu); do
+                echo $mem_by_cpu > /sys/block/zram$i/disksize
+                mkswap /dev/zram$i
+                swapon -p 100 /dev/zram$i
+        done
+fi
+
+if [ "$1" = "--unload" ] ; then
+        echo zram: Disable in-memory compressed swap.
+        for i in $(seq 0 $last_cpu); do
+                grep -q "/dev/zram$i" /proc/swaps && swapoff /dev/zram$i
+        done
+        
+        sleep 1
+        echo zram: Unload kernel module.
+        rmmod zram
+fi
diff --git a/recipes-core/systemd/rpi-zram-service/rpi-zram.service b/recipes-core/systemd/rpi-zram-service/rpi-zram.service
new file mode 100644
index 0000000..007dfcc
--- /dev/null
+++ b/recipes-core/systemd/rpi-zram-service/rpi-zram.service
@@ -0,0 +1,12 @@
+[Unit]
+Description=Enable zram compressed in-memory swap.
+After=multi-user.target
+
+[Service]
+RemainAfterExit=yes
+ExecStart=/usr/bin/rpi-load-zram.sh --load
+ExecStop=/usr/bin/rpi-load-zram.sh --unload
+Type=oneshot
+
+[Install]
+WantedBy=multi-user.target