Buffalo LinkStation LS220DE

This is a low-cost dual-port SATA NAS box. Very similar to LS421DE but with lower hardware specs. It comes with one 1GbE network port and one USB 2.0 host port on the back.

Stuff used in the installation:

• acp-commander: https://github.com/1000001101000/acp-commander

The box must have at least 1 hard drive installed in a bay. First check that the stock firmware is working ok. 192.168.1.11 is the IP of the device, 192.168.1.7 is the IP of our computer.

1. Use acp_commander to enable a root shell over telnet:

   java -jar acp_commander.jar -t 192.168.1.11 -pw password -o

2. Open a telnet session on the device:

   telnet 192.168.1.11

3. Backup the stock uImage:

    mv /boot/uImage.buffalo /boot/uImage.buffalo.bak

4. Download the Openwrt initramfs image and reboot:

   wget -O /boot/uImage.buffalo http://192.168.1.7:8000/openwrt-mvebu-cortexa9-buffalo_ls220de-initramfs-kernel.bin
   sync
   reboot

5. Now the device will load the Openwrt RAM image (not installed yet). Open a secure shell into Openwrt:

   ssh root@192.168.1.1

6. Rename boot files inside boot partition

   mount -t ext3 /dev/sda1 /mnt
   mv /mnt/uImage.buffalo /mnt/uImage.buffalo.openwrt.bak
   mv /mnt/initrd.buffalo /mnt/initrd.buffalo.bak

7. Format ubi partitions at the NAND flash (kernel_ubi and ubi):

   ubiformat /dev/mtd0
   ubidetach -p /dev/mtd1
   ubiformat /dev/mtd1

8. Download the sysupgrade image, and install it:

   cd /tmp
   wget http://192.168.1.7:8000/openwrt-mvebu-cortexa9-buffalo_ls220de-squashfs-sysupgrade.bin
   sysupgrade -n openwrt-mvebu-cortexa9-buffalo_ls220de-squashfs-sysupgrade.bin

9. Wait until it finish. The device will reboot with OpenWrt installed in the NAND flash
10. ssh to 192.168.1.1 and set a root password, or browse to http://192.168.1.1 if LuCI is installed.

Note: If you want to start using external storage see NAS configuration

• ipaddr: 192.168.11.150
• serverip: 192.168.11.1

1. Remove any hard drive inside the bays. Keep it apart if you want to go back to stock firmware later.
2. Boot the Openwrt initramfs image using the U-Boot serial console:

   tftpboot 0x1200000 openwrt-mvebu-cortexa9-buffalo_ls220de-initramfs-kernel.bin
   bootm 0x1200000

3. Format ubi partitions at the NAND flash (kernel_ubi and ubi):

   ubiformat /dev/mtd0
   ubidetach -p /dev/mtd1
   ubiformat /dev/mtd1

4. Flash the sysupgrade image using the Openwrt console:

   sysupgrade -n openwrt-mvebu-cortexa9-buffalo_ls220de-squashfs-sysupgrade.bin

5. Wait until it finish, the device will reboot with Openwrt installed on the NAND flash.

If you want to start using external storage insert a formatted hard drive inside the bay. The first partition should be never be in EXT4 filesystem format or it will hang at startup otherwise.

Tested partitioning configurations:

• OK: GPT, 1 partition
  • 1st: XFS, whole hard drive, storage partition
• OK: GPT, 2 partitions:
  • 1st: EXT3, 8MB, dummy partition
  • 2nd: EXT4, all remaining space, storage partition
• OK: GPT, 2 partitions:
  • 1st: SWAP, 1GB, virtual system memory.
  • 2nd: EXT4, all remaining space, storage partition
• OK: GPT, 2 partitions:
  • 1st: SWAP, 1GB, virtual system memory.
  • 2nd: XFS, all remaining space, storage partition
• FAIL: GPT, 1 partition
  • 1st: EXT4, whole hard drive, storage partition

You can use the original hard drive, but the boot partition contains uImage.buffalo and initrd.buffalo. You need to rename them to avoid booting from hardrive. The XFS partitions probably won't be recognized because they use the deprecated V4 version. You may need to reformat this partition or enable the V4 in the kernel (support until 2030).

• NAS (aka Network Attached Storage)
• Media Server (aka stream media to devices in your local network)
• Downloading and P2P Filesharing

Since this device is presumably used only for attached storage purposes, you can rid of firewall/routing stuff. Remove the firewall related kernel modules:

mkdir /etc/bak
mv /etc/modules.d/nf-* /etc/bak/
mv /etc/modules.d/ipt-* /etc/bak/
mv /etc/modules.d/*ip6tables* /etc/bak/
reboot

After rebooting, the network throughput should be about +15% better.

See → Cryptographic Hardware Accelerators

This device has a cypher engine called CESA. It can be used for libraries like openssl.

First install the openssl-util:

opkg update
opkg install openssl-util 

Make a test:

Now install the cryptodev module to make the engine available, also install the openssl library:

opkg update
opkg install kmod-cryptodev
opkg install libopenssl-devcrypto 

Open the /etc/ssl/openssl.cnf configuration file and uncomment these lines:

[engines]
devcrypto=devcrypto
 
[devcrypto] 
CIPHERS=DES-CBC, DES-EDE3-CBC, AES-128-CBC, AES-192-CBC, AES-256-CBC

Now make another test:

You can also optimize your firmware making your own custom build:

• Compile the kernel for single core (no SMP stuff).
• Compile the kernel in THUMB2 mode, and also the user space apps.
• Patch the kernel to enable the hardware I/O coherency.

If for some reason the bootloader is broken (no apparent life from the board), you can recover the device by using the UART serial port.

1. Connect the Linkstation's serial port to your computer
2. At the computer execute:

   ./kwboot -b uboot.uart -t -B 115200 /dev/ttyUSB0

3. Power on the Linkstation, wait for it to load.
4. At the Uboot console execute:

   bubt spiflash_134.bak

uImage.buffalo and initrd.buffalo are used to load a RAM firmware with the unique purpose of installing hddrootfs.buffalo on a SATA hard drive. Once decompressed it'll contain the whole operating system.

OpenWrt will use a more simple approach, installing the firmware in the NAND flash. No need of using an internal hard drive.

Casing

Opening the case

Board

→ port.serial general information about the serial port, serial port cable, etc.

→ port.jtag general information about the JTAG port, JTAG cable, etc.

Some boards experience random problems with the ethernet port. This bug is likely caused by an misconfigured voltage on the ethernet pins at the SoC.

• SoC: as default the RGMII pins are configured to operate at 3.3V
• PHY: the Marvel 88E1518 can only operate at 1.8V

It turns out that the SoC can be configured via internal registers to set the correct voltage on the RGMII pins.

There are three ways to fix this bug:

1. Setting the registers from userspace: it can be done using devmem. But it requires building a custom firmware with /dev/mem enabled in the kernel, and the utility devmem in busybox:

   devmem 0xd00184e0 32 0xa8a

2. Patching the bootloader: Flashing a new bootloader might brick your device.
3. Patching the kernel: this seems to be the best option. It won't require user intervention once Openwrt is installed. There is a patch already made for the kernel v5.4.41. But it wouldn't be accepted upstream. See: https://forum.openwrt.org/t/mvneta-help-with-a-voltage-patch/64226

The ethernet phy is EEE capable. Enabling this feature (using ethtool) may save some miliwatts. Example:

# ethtool --set-eee eth0 eee on

Check if it has been enabled:

# ethtool --show-eee eth0
EEE Settings for eth0:
        EEE status: active
        Tx LPI: disabled
        Supported EEE link modes:  100baseT/Full 
                                   1000baseT/Full 
        Advertised EEE link modes:  Not reported
        Link partner advertised EEE link modes:  100baseT/Full 
                                                 1000baseT/Full 

Only one LED pin at the IC is wired to a physical LED.

• LED0 has unknown use.
• LED1 pin is connected to a physical LED, and used to indicate ethernet link/activity.
• LED2 pin is used for poweroff function and maybe for Wake On LAN

• Doozan thread: Debian Stretch on Armada-370 Buffalo Devices

• Coherency fabric: it is disabled intentionally in the kernel. This might cause a performance loss. An attempt to reenable the coherence fabric: write-allocate cache policy is required, we also need to disable smp checks for the related stuff.

  --- a/arch/arm/mm/mmu.c
  +++ b/arch/arm/mm/mmu.c
  @@ -463,6 +463,12 @@
   			initial_pmd_value |= PMD_SECT_S;
   		}
   	}
  +#if defined(CONFIG_MACH_ARMADA_370)
  +	else if (cachepolicy != CPOLICY_WRITEALLOC) {
  +		pr_warn("Forcing write-allocate cache policy for Armada 370\n");
  +		cachepolicy = CPOLICY_WRITEALLOC;
  +	}
  +#endif
   
   	/*
   	 * Strip out features not present on earlier architectures.
  --- a/arch/arm/mach-mvebu/coherency.c
  +++ b/arch/arm/mach-mvebu/coherency.c
  @@ -226,8 +226,6 @@
   	 * where we don't know yet on which SoC we are running.
   
   	 */
  -	if (!is_smp())
  -		return COHERENCY_FABRIC_TYPE_NONE;
   
   	np = of_find_matching_node_and_match(NULL, of_coherency_table, &match);
   	if (!np)
  --- a/arch/arm/mm/proc-v7-2level.S
  +++ b/arch/arm/mm/proc-v7-2level.S
  @@ -16,9 +16,9 @@
   #define TTB_IRGN_WT	((1 << 0) | (0 << 6))
   #define TTB_IRGN_WB	((1 << 0) | (1 << 6))
   
  -/* PTWs cacheable, inner WB not shareable, outer WB not shareable */
  -#define TTB_FLAGS_UP	TTB_IRGN_WB|TTB_RGN_OC_WB
  -#define PMD_FLAGS_UP	PMD_SECT_WB
  +/* PTWs cacheable, inner WBWA not shareable, outer WBWA not shareable */
  +#define TTB_FLAGS_UP	TTB_IRGN_WBWA|TTB_RGN_OC_WBWA
  +#define PMD_FLAGS_UP	PMD_SECT_WBWA
   
   /* PTWs cacheable, inner WBWA shareable, outer WBWA not shareable */
   #define TTB_FLAGS_SMP	TTB_IRGN_WBWA|TTB_S|TTB_NOS|TTB_RGN_OC_WBWA
  --- a/arch/arm/mm/proc-v7.S
  +++ b/arch/arm/mm/proc-v7.S
  @@ -444,6 +444,7 @@
   	/* Auxiliary Debug Modes Control 1 Register */
   	mrc	p15, 1,	r0, c15, c1, 1
   	orr     r0, r0, #PJ4B_CLEAN_LINE
  +	orr     r0, r0, #(1 << 7)		@ v7 IO coherency support (Single core). Taken from vendor's GPL.
   	orr     r0, r0, #PJ4B_INTER_PARITY
   	bic	r0, r0, #PJ4B_STATIC_BP
   	mcr	p15, 1,	r0, c15, c1, 1

  After re-compiling the kernel without netfilter modules and testing, the network throughput is about 20% better.

• Suspend: CONFIG_SUSPEND isn't enabled by default in the OpenWrt kernel. After enabling it in a custom firmware, we can call the suspend command:

  echo -n s2idle > /sys/power/mem_sleep
  echo -n mem > /sys/power/state

  But the machine isn't able to remain suspended, it reboots after the suspend sequence.

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