MNT Reform

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Hardware

root #lspci
0000:00:00.0 PCI bridge: Synopsys, Inc. DWC_usb3 / PCIe bridge (rev 01)
0000:01:00.0 Network controller: Qualcomm Atheros AR928X Wireless Network Adapter (PCI-Express) (rev 01)
0001:00:00.0 PCI bridge: Synopsys, Inc. DWC_usb3 / PCIe bridge (rev 01)
0001:01:00.0 Non-Volatile memory controller: Silicon Motion, Inc. Device 2263 (rev 03)
root #lsusb
Bus 001 Device 006: ID 03eb:2042 Atmel Corp. LUFA Keyboard Demo Application
Bus 004 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 001 Device 005: ID 03eb:2041 Atmel Corp. LUFA Mouse Demo Application
Bus 001 Device 002: ID 0451:8142 Texas Instruments, Inc. TUSB8041 4-Port Hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 002 Device 002: ID 0451:8140 Texas Instruments, Inc. TUSB8041 4-Port Hub
Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
root #cat /proc/cpuinfo
processor	: 0
BogoMIPS	: 16.66
Features	: fp asimd evtstrm aes pmull sha1 sha2 crc32 cpuid
CPU implementer	: 0x41
CPU architecture: 8
CPU variant	: 0x0
CPU part	: 0xd03
CPU revision	: 4

processor	: 1
BogoMIPS	: 16.66
Features	: fp asimd evtstrm aes pmull sha1 sha2 crc32 cpuid
CPU implementer	: 0x41
CPU architecture: 8
CPU variant	: 0x0
CPU part	: 0xd03
CPU revision	: 4

processor	: 2
BogoMIPS	: 16.66
Features	: fp asimd evtstrm aes pmull sha1 sha2 crc32 cpuid
CPU implementer	: 0x41
CPU architecture: 8
CPU variant	: 0x0
CPU part	: 0xd03
CPU revision	: 4

processor	: 3
BogoMIPS	: 16.66
Features	: fp asimd evtstrm aes pmull sha1 sha2 crc32 cpuid
CPU implementer	: 0x41
CPU architecture: 8
CPU variant	: 0x0
CPU part	: 0xd03
CPU revision	: 4

f0 respawning

With a default arm64 system, error messages like this will appear both on the default TTY in the system log:

Id "f0" respawning too fast: disabled for 5 minutes

To get rid of those, edit the inittab at /etc/inittab and remove or comment out the last line, that looks something like this:

FILE /etc/inittab
# Architecture specific features
f0:12345:respawn:/sbin/agetty 9600 ttyAMA0 vt100

Then, restart the system.

Clock loses time on reboot

The Reform has two Real-time clocks installed in the system - a battery backed up PCF8523 and an on-CPU SNVS. The SNVS clock is powered by the same rail as the i.MX8M CPU and will reset together with the system. By default, the hwclock is using /dev/rtc0, which might be the wrong clock.

To fix this issue, either remove the rtc-snvs kernel driver, or edit the following line in /etc/conf.d/hwclock

FILE /etc/conf.d/hwclock
clock_args="--rtc /dev/rtc1"

Check which RTC has been assigned to which device by looking at the kernel ring buffer:

user $ dmesg | grep --ignore-case rtc
[    3.556883] rtc-pcf8523 2-0068: registered as rtc0
[    3.563641] rtc-pcf8523 2-0068: setting system clock to 2020-07-13T17:27:26 UTC (1594661246)

In the above example, the PCF8523 is the only RTC and it is assigned to /dev/rtc0.

Boot from (internal) eMMC using initrd

At some point you will probably want to be able to start the laptop without having an SD card inserted. Also, if you are booting from an encrypted disk, which really you should, you will need a mechanism to open the disk at startup. This chapter will explain how you can achieve both of these goals.