Tech Memorandums

Building a Digital Homestead: Chapter 2

The computer was born to solve problems that did not exist before. — Bill Gates

Booting the HC2

Building a rootfs

Buildroot at the time of writing did not have support for the Odroid HC2/XU4. It did have support for the Odroid C2. It turns out that some kind folks have added support for the XU4. I check out this branch and start building.

$ make odroidxu4_defconfig
$ make nconfig

The first command sets up a .config with some defaults. You can tweak this config with nconfig. I setup a debug build and because of that had to increase the size of the rootfs to 120M. I also set BR2_JLEVEL=3 in .config to enable parallel makes. One does not simply make -jN at the top level. I did not twiddle any other knobs as I just wanted to get the HC2 to boot first and then I’d see about customising the build.

While it was building, I read up on HT and parallel makes. In short, feel free to set this to number of HT cores + 1.

After crunching away for about 30 mins, it gave me an image. I remember doing a similar thing back in 2006 for the sheevaplug and it took me a week of cursing and blind hacking to get to this stage.

HC2 PXE boot

The HC2 can only boot from the SD card. It is therefore necessary to configure u-boot on the SD card to PXE boot. I found a pxeboot article on the odroid wiki and adapted it to my needs.

I used one of the odroid provided microSD cards, hoping that it would already have the latest u-boot. So I just needed to replace boot.ini. The important stuff is the last few lines.

ODROIDXU-UBOOT-CONFIG

# U-Boot Parameters
setenv initrd_high "0xffffffff"
setenv fdt_high "0xffffffff"

# Mac address configuration
setenv macaddr "00:1e:06:61:7a:39"

#------------------------------------------------------------------------------------------------------
# Basic Ubuntu Setup. Don't touch unless you know what you are doing.
# --------------------------------
setenv bootrootfs "console=tty1 console=ttySAC2,115200n8 root=UUID=e139ce78-9841-40fe-8823-96a304a09859 rootwait ro fsck.repair=yes net.ifnames=0"

# --- Screen Configuration for HDMI --- # 
# ---------------------------------------
# Uncomment only ONE line! Leave all commented for automatic selection.
# Uncomment only the setenv line!
# ---------------------------------------
# ODROID-VU forced resolution
# setenv videoconfig "video=HDMI-A-1:1280x800@60"
# -----------------------------------------------
# ODROID-VU forced EDID
# setenv videoconfig "drm_kms_helper.edid_firmware=edid/1280x800.bin"
# -----------------------------------------------
# 1920x1200 60hz without monitor data using generic information
# setenv videoconfig "drm_kms_helper.edid_firmware=edid/1920x1200_60hz.bin"
# -----------------------------------------------
# 1920x1200 30hz without monitor data using generic information
# setenv videoconfig "drm_kms_helper.edid_firmware=edid/1920x1200_30hz.bin"
# -----------------------------------------------
# 1920x1080 (1080P) with monitor provided EDID information. (1080p-edid)
# setenv videoconfig "video=HDMI-A-1:1920x1080@60"
# -----------------------------------------------
# 1920x1080 (1080P) without monitor data using generic information (1080p-noedid)
# setenv videoconfig "drm_kms_helper.edid_firmware=edid/1920x1080.bin"
# -----------------------------------------------
# 1920x1080 50hz (1080P) with monitor provided EDID information. (1080p 50hz-edid)
# setenv videoconfig "video=HDMI-A-1:1920x1080@50"
# -----------------------------------------------
# 1920x1080 50hz (1080P) without monitor data using generic information (1080p 50hz-noedid)
# setenv videoconfig "drm_kms_helper.edid_firmware=edid/1920x1080_50hz.bin"
# -----------------------------------------------
# 1680x1050 without monitor data using generic information 
# setenv videoconfig "drm_kms_helper.edid_firmware=edid/1680x1050.bin"
# -----------------------------------------------
# 1600x1200 without monitor data using generic information 
# setenv videoconfig "drm_kms_helper.edid_firmware=edid/1600x1200.bin"
# -----------------------------------------------
# 1600x900 without monitor data using generic information 
# setenv videoconfig "drm_kms_helper.edid_firmware=edid/1600x900.bin"
# -----------------------------------------------
# 1440x900 with monitor provided EDID information.
# setenv videoconfig "video=HDMI-A-1:1440x900@60"
# -----------------------------------------------
# 1440x900 without monitor data using generic information 
# setenv videoconfig "drm_kms_helper.edid_firmware=edid/1440x900.bin"
# -----------------------------------------------
# 1366x768 without monitor data using generic information 
# setenv videoconfig "drm_kms_helper.edid_firmware=edid/1366x768.bin"
# -----------------------------------------------
# 1360x768 without monitor data using generic information 
# setenv videoconfig "drm_kms_helper.edid_firmware=edid/1360x768.bin"
# -----------------------------------------------
# 1280x1024 without monitor data using generic information
# setenv videoconfig "drm_kms_helper.edid_firmware=edid/1280x1024.bin"
# -----------------------------------------------
# 1280x720 (720P) with monitor provided EDID information. (720p-edid)
# setenv videoconfig "video=HDMI-A-1:1280x720@60"
# -----------------------------------------------
# 1280x720 (720P) without monitor data using generic information (720p-noedid)
# setenv videoconfig "drm_kms_helper.edid_firmware=edid/1280x720.bin"
# -----------------------------------------------
# 1024x768 without monitor data using generic information
# setenv videoconfig "drm_kms_helper.edid_firmware=edid/1024x768.bin"
# -----------------------------------------------
# 1024x600 without monitor data using generic information (ODROID VU7+)
# setenv videoconfig "drm_kms_helper.edid_firmware=edid/1024x600.bin"
# -----------------------------------------------
# 800x600 without monitor data using generic information 
# setenv videoconfig "drm_kms_helper.edid_firmware=edid/800x600.bin"
# -----------------------------------------------
# 800x480 without monitor data using generic information (ODROID 7")
# setenv videoconfig "drm_kms_helper.edid_firmware=edid/800x480.bin"
# -----------------------------------------------
# 720x576 without monitor data using generic information 
# setenv videoconfig "drm_kms_helper.edid_firmware=edid/720x576.bin"
# -----------------------------------------------
# 720x480 without monitor data using generic information 
# setenv videoconfig "drm_kms_helper.edid_firmware=edid/720x480.bin"
# -----------------------------------------------
# 640x480 without monitor data using generic information
# setenv videoconfig "drm_kms_helper.edid_firmware=edid/640x480.bin"
# -----------------------------------------------
# 480x800 without monitor data using generic information
# setenv videoconfig "drm_kms_helper.edid_firmware=edid/480x800.bin"
# -----------------------------------------------
# 480x320 without monitor data using generic information
# setenv videoconfig "drm_kms_helper.edid_firmware=edid/480x320.bin"


# --- HDMI / DVI Mode Selection ---
# ------------------------------------------
# - HDMI Mode
setenv vout "hdmi"
# - DVI Mode (disables sound over HDMI as per DVI compat)
# setenv vout "dvi"


# --- HDMI CEC Configuration ---
# ------------------------------------------
setenv cecenable "false" # false or true
# set to true to enable HDMI CEC


# --- CPU Governor Setup ---
# Uncomment only one line. New governor is set after 90secs after boot.
# ------------------------------------------
# - Performance (Keep all the CPU's at Maximum frequency)
setenv governor "performance"
# ------------------------------------------
# - Ondemand
# setenv governor "ondemand"
# ------------------------------------------
# - Interactive (Pretty much just like ondemand with more possible customization via sysfs.)
# setenv governor "interactive"
# ------------------------------------------
# - Conservative (Like ondemand, but do the frequency transitions more slowly, great for battery powered applications)
# setenv governor "conservative"
# ------------------------------------------
# - Powersave (Keeps the CPU's to the lowest possible temps)
# setenv governor "powersave"

# Enable/Disable ODROID-VU7 Touchsreen
setenv disable_vu7 "false" # false


#------------------------------------------------------------------------------
#
# HDMI-PHY Parameter Control
#
#------------------------------------------------------------------------------
#------------------------------------------------------------------------------
#
# HDMI Hot Plug detection
#
#------------------------------------------------------------------------------
#
# Forces the HDMI subsystem to ignore the check if the cable is connected or 
# not.
# false : disable the detection and force it as connected.
# true : let cable, board and monitor decide the connection status.
# 
# default: true
# 
#------------------------------------------------------------------------------
setenv HPD "true"

#------------------------------------------------------------------------------
#
#  TMDS data amplitude control.
#
#------------------------------------------------------------------------------
#
#  1LSB corresponds to 20 mVdiff amplitude level.
#  tx_amp_lvl : 0 = 760 mVdiff(Min), 31 = 1380 mVdiff(Max)
#
#  Hardkernel default hdmi_tx_amp_lvl = 31(1380 mVdiff);
#------------------------------------------------------------------------------
setenv hdmi_tx_amp_lvl  "31"

#------------------------------------------------------------------------------
#
#  TMDS data amplitude fine control for each channel.
#
#------------------------------------------------------------------------------
#
#  1LSB corresponds to 20 mVdiff amplitude level.
#  tx_lvl : 0 = 0 mVdiff(Min), 3 = 60 mVdiff(Max)
#
#  Hardkernel default
#      hdmi_tx_lvl_ch0 = 3, hdmi_tx_lvl_ch1 = 3, hdmi_tx_lvl_ch2 = 3,
#------------------------------------------------------------------------------
setenv hdmi_tx_lvl_ch0      "3"
setenv hdmi_tx_lvl_ch1      "3"
setenv hdmi_tx_lvl_ch2      "3"

#------------------------------------------------------------------------------
#
#  TMDS data pre-emphasis level control.
#
#------------------------------------------------------------------------------
#
#  1LSB corresponds to -0.45dB emphasis level except for 1
#  tx_emp_lvl : 0 = 0 db(Min), 1 = -0.25 db, 2 = 0.7 db, 15 = -7.45 db(Max)
#
#  Hardkernel default hdmi_tx_emp_lvl = 6 (-2.50 db);
#------------------------------------------------------------------------------
setenv hdmi_tx_emp_lvl      "6"

#------------------------------------------------------------------------------
#
#  TMDS clock amplitude control.
#
#------------------------------------------------------------------------------
#
#  1LSB corresponds to 20 mVdiff amplitude level.
#  clk_amp_lvl : 0 = 790 mVdiff(Min), 31 = 1410 mVdiff(Max)
#
#  Hardkernel default hdmi_clk_amp_lvl = 31 (1410 mVdiff)
#------------------------------------------------------------------------------
setenv hdmi_clk_amp_lvl     "31"

#------------------------------------------------------------------------------
#
#  TMDS data source termination resistor control.
#
#------------------------------------------------------------------------------
#
#  tx_res :
#      0 = Source Termination OFF(Min), 1 = 200 ohm, 2 = 300 ohm, 3 = 120 ohm(Max)
#
#  Hardkernrel default hdmi_tx_res = 0 (Source Termination OFF)
#------------------------------------------------------------------------------
setenv hdmi_tx_res      "0"

#------------------------------------------------------------------------------

setenv hdmi_phy_control "hdmi_tx_amp_lvl=${hdmi_tx_amp_lvl} hdmi_tx_lvl_ch0=${hdmi_tx_lvl_ch0} hdmi_tx_lvl_ch1=${hdmi_tx_lvl_ch1} hdmi_tx_lvl_ch2=${hdmi_tx_lvl_ch2} hdmi_tx_emp_lvl=${hdmi_tx_emp_lvl} hdmi_clk_amp_lvl=${hdmi_clk_amp_lvl} hdmi_tx_res=${hdmi_tx_res} HPD=${HPD} vout=${vout}"


# Load kernel, initrd and dtb in that sequence
fatload mmc 0:1 0x40008000 zImage
fatload mmc 0:1 0x42000000 uInitrd
fatload mmc 0:1 0x44000000 exynos5422-odroidxu3.dtb

# set FDT address
fdt addr 0x44000000

if test "${cecenable}" = "false"; then fdt rm /cec@101B0000; fi
if test "${disable_vu7}" = "false"; then setenv hid_quirks "usbhid.quirks=0x0eef:0x0005:0x0004"; fi

# final boot args
setenv bootargs "${bootrootfs} ${videoconfig} smsc95xx.macaddr=${macaddr} governor=${governor} ${hdmi_phy_control} ${hid_quirks}"

# Boot the board
#bootz 0x40008000 0x42000000 0x44000000

setenv serverip 192.168.1.42
setenv bootfile default-arm-exynos
run bootcmd_pxe

The cubox already has tftp from the x61s restore. I wasn’t sure how to have two independant boot configs so I just backed up the existing config to ~/var/pkgs/ and created a new structure.

$ cd /srv/tftp
$ mkdir odroidxu4
$ mkdir pxelinux.cfg
$ cat > pxelinux.cfg/default-arm-exynos
DEFAULT odroidxu4_default

LABEL odroidxu4_default
kernel odroidxu4/zImage
fdt odroidxu4/exynos5422-odroidxu4.dtb
append console=tty1 console=ttySAC2,115200n8 root=/dev/ram0 rootwait rw net.ifnames=0 fsck.repair=yes
initrd odroidxu4/rootfs.cpio

PROMPT 1
TIMEOUT 0
^D

Now, the kernel and dtb from the buildroot step above.

$ cd ~/src/verium-miner/output/images
$ scp exynos5422-odroidxu4.dtb zImage rootfs.cpio cubox:/tmp/q

Then, on the cubox, as tftp,

$ cd /srv/tftp
$ cp /tmp/q/* odroidxu4