Basic diagnostics kernel
Basic diagnostics kernel is not the same thing as diagnostics mode. Those are 2 separate things. This on described on this page is more low level and has some other features
This page describes the "Basic Diagnostics Kernel" that can be found on
some supported devices. It includes a small set of tools that can be
used to restore the device from scratch if something goes wrong.
Booting on the Basic Diagnostics Kernel (BDK) is supported on devices with two or more physical buttons. The current list is as follows:
- Kobo Touch B/C
- Kobo Glo
In the bootloader code of supported devices, there is a specific action
triggered when the secondary button (e.g. Home button or brightness
button) is pressed whilst the bootloader is still loading. In Quill OS,
this code has been modified so that it can load a different kernel,
stored at a different sector of the MMC.
Usually, the default Quill OS kernel load sector is 81920. However,
when the secondary button is pressed, it changes to 19456, at which
position in the MMC is contained the BDK.
Here is a sample serial port log from a device booting the BDK:
U-Boot 2009.08-inkbox (Feb 14 2022 - 19:03:20)
CPU: Freescale i.MX50 family 1.1V at 800 MHz
mx50 pll1: 800MHz
mx50 pll2: 400MHz
mx50 pll3: 216MHz
ipg clock : 66666666Hz
ipg per clock : 66666666Hz
uart clock : 24000000Hz
ahb clock : 133333333Hz
axi_a clock : 400000000Hz
axi_b clock : 200000000Hz
weim_clock : 100000000Hz
ddr clock : 200000000Hz
esdhc1 clock : 80000000Hz
esdhc2 clock : 80000000Hz
esdhc3 clock : 80000000Hz
esdhc4 clock : 80000000Hz
Board: MX50 RDP board
Boot Reason: [POR]
Boot Device: SD
I2C: ready
DRAM: 256 MB
MMC: FSL_ESDHC: 0, FSL_ESDHC: 1
In: serial
Out: serial
Err: serial
MMC read: dev # 0, block # 1023, count 1 partition # 0 ...
1 blocks read: OK
MMC read: dev # 0, block # 1024, count 1 partition # 0 ...
1 blocks read: OK
[only 1 key]
1 keys,0x00,0x01
**************************************
** Boot to basic diagnostics mode **
**************************************
ram p=70000000,size=268435456
MMC read: dev # 0, block # 1023, count 1 partition # 0 ...
1 blocks read: OK
MMC read: dev # 0, block # 1024, count 1 partition # 0 ...
1 blocks read: OK
MMC read: dev # 0, block # 18431, count 1 partition # 0 ...
1 blocks read: OK
MMC read: dev # 0, block # 14335, count 1 partition # 0 ...
1 blocks read: OK
MMC read: dev # 0, block # 14336, count 1899 partition # 0 ...
1899 blocks read: OK
Kernel RAM visiable size=255M->255M
Hit any key to stop autoboot: 0
Valid chip addresses: 00 43
MMC read: dev # 0, block # 19455, count 1 partition # 0 ...
1 blocks read: OK
cmd=mmc read 0 0x7781f9f8 0x4bff 0x1
no kernel image signature !
cmd=mmc read 0 0x70800000 0x4c00 0x4800
MMC read: dev # 0, block # 19456, count 18432 partition # 0 ...
18432 blocks read: OK
## Booting kernel from Legacy Image at 70800000 ...
Image Name: Linux-2.6.35.3-inkbox+
Image Type: ARM Linux Kernel Image (uncompressed)
Data Size: 5019952 Bytes = 4.8 MB
Load Address: 70008000
Entry Point: 70008000
Loading Kernel Image ... OK
OK
Starting kernel ...
Uncompressing Linux... done, booting the kernel.
*** InkBox system diagnostics ***
Version 1.0, built Sun Mar 6 2022
Available options:
1 - System Info
2 - Battery Info
3 - Graphics test
4 - Memory test
5 - Utilities
6 - Reboot
7 - Power off
8 - Exit to shell
Diagnostics =>
As shown above, we get to a Diagnostics => prompt, which tells us the
BDK is fully started and ready to receive commands.
In the BDK, often the state of operations and commands executed is shown on the screen, but input is only possible via the serial port. This sections describes how to interact with the BDK.
The main menu presents a list of
the possible recovery options we could want to use.
The following explains in detail what each option does.
Serial console
*** InkBox system diagnostics ***
Version 1.0, built Sun Mar 6 2022
Available options:
1 - System Info
2 - Battery Info
3 - Graphics test
4 - Memory test
5 - Utilities
6 - Reboot
7 - Power off
8 - Exit to shell
Diagnostics =>
Displays information about
the running system, such as the kernel version, device identifier (e.g.
n905b), root status (c.f.
General_information#Standard_and_Rooted),
firmware version, time, memory info and processor info.
Serial console
Diagnostics => 1
---- General info ----
Kernel version: 2.6.35.3-inkbox+
Device: n905b
Status: Rooted
F/W version: 1.9
Time: Mon Mar 7 22:19:38 UTC 2022
---- Memory info ----
MemTotal: 253924 kB
MemFree: 194392 kB
---- Processor info ----
Architecture: armv7l
< OK >
Displays information
about the battery status and charge.
Serial console
Diagnostics => 2
Battery status: Charging
Battery level: 90%
< OK >
Does a graphics
test.
Serial console
Diagnostics => 3
Is the gray scale displayed properly? (Y/N) Y
Test summary:
Gray scale: PASS
< OK >
Does a memory test.
Serial console
Diagnostics => 4
Found 253924 kB of RAM.
Using 126962 kB.
Memory test started.
memtester version 4.5.0 (32-bit)
Copyright (C) 2001-2020 Charles Cazabon.
Licensed under the GNU General Public License version 2 (only).
pagesize is 4096
pagesizemask is 0xfffff000
want 123MB (130009088 bytes)
got 123MB (130009088 bytes), trying mlock ...locked.
Loop 1/1:
Stuck Address : ok
Random Value : ok
Compare XOR : ok
Compare SUB : ok
Compare MUL : ok
Compare DIV : ok
Compare OR : ok
Compare AND : ok
Sequential Increment: ok
Solid Bits : ok
Block Sequential : ok
Checkerboard : ok
Bit Spread : ok
Bit Flip : ok
Walking Ones : ok
Walking Zeroes : ok
8-bit Writes : ok
16-bit Writes : ok
Done.
... Redundant output cut ...
< OK >
The
Utilities option is a subsystem containing various utilities permitting
to fully recover the device from the serial port. These options are
described below.
Flashes a
kernel to the (e)MMC. The kernel is loaded on the serial port via the
XMODEM protocol and then flashed at sector 81920 or 19456 of the
(e)MMC, depending on the user's choice.
Serial console
Utilities => 1
An XMODEM receiver is now listening on the serial port. Please send the file now and strike CTRL+D when the transfer finishes.
Flash 'main' or 'diagnostics' kernel? main
Flashing MAIN kernel ...
OK: Kernel flashed.
< OK >
Flashes
the U-Boot bootloader to the (e)MMC. U-Boot is loaded on the serial port
via the XMODEM protocol and then flashed at the second 1K sector of
the (e)MMC.
Serial console
Utilities => 2
An XMODEM receiver is now listening on the serial port. Please send the file now and strike CTRL+D when the transfer finishes.
Flashing U-Boot ...
OK: U-Boot flashed.
< OK >
WARNING: This option should
never be used, unless you know exactly what you are doing.
Completely erases the (e)MMC and restores the first unpartitioned space,
which includes U-Boot.
Serial console
Utilities => 3
CAUTION! This will erase EVERYTHING on the MMC, excluding U-Boot. You have been warned.
Continue? (Y/N) Y
Reboots the device.
Serial console
Diagnostics => 6
Rebooting ...
The system is going down NOW!
Sent SIGTERM to all processes
Sent SIGKILL to all processes
Requesting system reboot
[ 105.285660] Restarting system.
Powers off the device.
Serial console
Diagnostics => 7
Shutting down ...
The system is going down NOW!
Sent SIGTERM to all processes
Sent SIGKILL to all processes
Requesting system poweroff
[ 7.459963] Power down.
Spawns a shell,
allowing you to run standard Linux commands in a minimal environment.
Serial console
Diagnostics => 8
---- Exited to shell ----
/ # cat /proc/version
Linux version 2.6.35.3-inkbox+ (build@inkbox) (gcc version 4.8.1 20130401 (prerelease) (crosstool-NG linaro-1.13.1-4.8-2013.04-20130417 - Linaro GCC 2013.04) ) #1 PREEMPT Sun Mar 6 14:50:52 EST 2022
/ # uptime
23:04:41 up 5 min, 0 users, load average: 0.99, 0.64, 0.27
/ # date
Mon Mar 7 23:04:46 UTC 2022
/ #