Fink's Taxonomy of Significant Learning

Fink (2013) proposes a taxonomy of significant learning that he synthesizes from decades of conversations with students and teachers on the topic of significant learning whose examples include, "learning how to learn, leadership and interpersonal skills, ethics, communication skills, character, tolerance, and the ability to adapt to change." (Fink, 2013) This taxonomy has the following categories,

• Foundational Knowledge
  Understanding and remembering:
  
  • Information
  • Ideas
• Application
  
  • Skills
  • Thinking (Critical, creative and practical thinking
  • Managing projects
• Integration
  Connecting:
  
  • Ideas
  • People
  • Realms of life
• Human Dimension
  Learning about:
  
  • Oneself
  • Others
• Caring
  Developing new:
  
  • Feelings
  • Interests
  • Values
• Learning How to Learn
  
  • Becoming a better student
  • Inquiring about a subject
  • Self-directing learners

Reference [1] Fink, L.D., 2013. Creating significant learning experiences: An integrated approach to designing college courses. John Wiley & Sons.

Problem: Baseboard management controller cannot get IP address?

I have a computer system whose motherboard has ASRock Rack baseboard management controller (BMC) that allows me to interact with the system via the Intelligent Platform Management Interface (PMI). One day, I noticed that the BMC ceases to have an IP address assigned. This is obviously a problem since the system does not have a monitor directly connect to it, and the management console was at the time the only means for me to administrate the system fully.

Neither of the following I attempted resolved the issue,

1. I unplug and re-plug the Ethernet cable to the Ethernet port of the BMC.
2. I reboot the network gateway that runs the DHCP server to allocate the IP address to it.
3. I shutdown the system, and reboot the system.  

Finally, I realized that the BMC is a little computer of its own, and I had never rebooted it at all despite the above attempts. With this in mind, I attempted the following solution and it worked!

• Unplug the power cable from the system and plug the power cable back to the system

This in retrospect is the means to reboot the BMC system. Having attempted this, I also wonder, what if I switch off the power switch of the power supply, would it also work? I guess it should be, it reboots the BMC system itself to cut off the power. So simple, after some frustration!

"git status" shows modifications, but "git diff" shows nothing

I encountered a strange problem about a git repository today, that is, when I do a git status, git reports there are modifications. However, when I do a git diff, git reports no difference, like the following,

$ git status .
On branch master
Your branch is up to date with 'origin/master'.

Changes not staged for commit:
  (use "git add ..." to update what will be committed)
  (use "git checkout -- ..." to discard changes in working directory)

        modified:   .gitignore

$ git diff
$

After a little bit digging, apparently a few others encountered the same problem as a Stack Overflow discussion indicates.

The cause of my case are two,

1. Some files have different line endings from the version in the repository as a result that I was working on a Windows Subsystem for Linux and had the git's configuration property core.autocrlf set as input. I revealed the Windows line ending using vim, as in the following,
   

   
   $ vim -b .gitignore
   # Compiled class file^M
   *.class^M
   ^M
   # Log file^M
   *.log^M
   ^M
   # BlueJ files^M
   *.ctxt^M
   

   
   where the ^M characters are the Windows line endings, i.e., CR LF. I got rid of the line endings using sed, as in,
   

   
    sed -i -e s/^M// .gitignore
   

   
   Note that we enter the line ending by pressing CRTL-V CRTRL-M
   
2. The second issue is that some files have different permissions from those in the repository. Since I was using a Windows Subsystem for Linux on a Windows host, it is difficult for me to set the permissions identical to those in the repository. However, we can let git to ignore permission difference, i.e.,
   

   
   git config --local core.filemode false
   

   
   where I only did this for the repository. If we wish to do this for globally for all repositories, just issue the command without the --local option.

Problem: Application Icon on Windows Taskbar Becomes White Square

I was using a Windows 10 system. I noticed somehow the icon of application on the taskbar became a white square, like this picture shows,

I figured out a solution to resolve this. That is to delete the thumbnail icon cache that we can find at %LOCALAPPDATA%\Microsoft\Windows\Explorer, i.e.,

1. Open a Windows Command Prompt window
2. Do the following from the command line on the Windows Command Prompt window
1. taskkill /F /IM explorer.exe
2. del %LOCALAPPDATA%\Microsoft\Windows\Explorer\thumbcache_*.db
3. explorer.exe

Sometimes, it is also necessary to remove all the thumbnails themselves, i.e., run the Disk Cleanup application. From the command line, that is,

1. Run the Disk Cleanup application, i.e., cleanmgr.exe
2. Uncheck everything using the user interface, and check "Thumbnails" (See the screen shot). 
3. Click OK to confirm
4. Exit the Disk Cleanup application

The system will rebuild the thumbnail cache and the thumbnails.

Problem: Keyboard Input Echoed Back to Serial Terminal using PuTTY to Linux System

I enabled the serial console on a Debian Linux system. I used PuTTY to connect to the serial console. However, I encountered a problem, i.e., any keyboard inputs were echoed back to the serial console. The following screen shot perhaps explains the problem, e.g., when I enter user name, the user name is echoed back again, and when I enter the password, by default, the terminal shouldn't show anything, but it echoes it back.

 

A Stack Overflow thread discusses a similar problem, and I linked it below,

•  PuTTY serial communication

The thread led me to experimenting the terminal setting in PuTTY. The default setting of the "Line discipline options" is "Auto" for "Local echo", and "Auto" for "Local line editing" shown in the screen capture below. When using these settings, I encountered the problem I described in the above.

My fiddling with the settings tells me that the solution is to check "Force off"  for "Local echo", and "Force off" for "Local line editing" shown in the screen shot below,

Having made the setting changes, I saw that the problem went away. Well, we can see it from the screen shot below,

Adding new disk to a system? MBR Partition Table or GUID Partition Table?

I wanted to add a new virtual harddisk drive to a Debian Linux system on an Oracle VirtualBox virtual machine. A little bit planning goes a long way. One question we ought to ask is, what type of partition table should we choose?

For PCs, there are two types of partitions one can choose from,

1. Master Boot Record Partition Table (MBR Partition Table, or MBR), and
2. GUID Partition Table (GPT).

The former was developed in 1980's with DOS and enjoys a wide support, but has a major limitation.  The major limitation is rooted from the fact that the logical address to a sector on a MBR partition is 32-bit wide. Given sector size is 512 bytes, the largest partition is limited to

2³²*512=2⁴¹=2*2⁴⁰=2 TB

To overcome this limitation, GPT uses 64-bit logical addresses. This arguably allows us to address the number of bytes of an astronomical scale.

Master Boot Record Partition Table

The complete process of adding a harddisk drive to a Debian Linux sytem using the MBR partition is as follows,

1. Look up the name the attached harddisk drive using lsblk
2. Create an extended partition using the fdisk tool
3. Create a logical partition on the extended partition using the fdisk tool
4. Create a file system on the logical partition
5. Mount the file system and use it

This method is in fact similar to the method to create GUID partition table. The details are thus skipped here.

GUID Partition Table

There are a couple of tools we can use to create GUID partition tables, e.g.,

• fdisk. The new version of fdisk has GPT support. We can know whether the version installed in the system has the GPT support by viewing its manual page, e.g., the manual page of the version of fdisk on the Linux system I am using states,
  
  "
  

  fdisk is a dialog-driven program for creation and manipulation of partition tables. It understands GPT, MBR, Sun, SGI and BSD partition tables.

  "
• gdisk. It is a tool much like fdisk. The manual page states that it is a
  
  "
  

  GPT fdisk (aka gdisk) is a text-mode menu-driven program for creation and manipulation of partition tables.

  "
• parted. This is a more powerful tool than fdisk and gdisk.

Below we show 3 examples using these 3 tools to create a GPT.

Using fdisk

1. Look up the name the attached harddisk drive using lsblk
2. Create a GPT.
   

   
   $ sudo fdisk /dev/sdb
   
   Welcome to fdisk (util-linux 2.33.1).
   Changes will remain in memory only, until you decide to write them.
   Be careful before using the write command.
   
   Command (m for help): m
   
   Help:
   
     GPT
      M   enter protective/hybrid MBR
   
     Generic
      d   delete a partition
      F   list free unpartitioned space
      l   list known partition types
      n   add a new partition
      p   print the partition table
      t   change a partition type
      v   verify the partition table
      i   print information about a partition
   
     Misc
      m   print this menu
      x   extra functionality (experts only)
   
     Script
      I   load disk layout from sfdisk script file
      O   dump disk layout to sfdisk script file
   
     Save & Exit
      w   write table to disk and exit
      q   quit without saving changes
   
     Create a new label
      g   create a new empty GPT partition table
      G   create a new empty SGI (IRIX) partition table
      o   create a new empty DOS partition table
      s   create a new empty Sun partition table
   
   
   Command (m for help): g
   
   Created a new GPT disklabel (GUID: 08486B58-59CB-E849-B814-38DD8434D43C).
   
   Command (m for help): n
   Partition number (1-128, default 1):
   First sector (2048-32767966, default 2048):
   Last sector, +/-sectors or +/-size{K,M,G,T,P} (2048-32767966, default 32767966):
   
   Created a new partition 1 of type 'Linux filesystem' and of size 15.6 GiB.
   Partition #1 contains a ext4 signature.
   $
   

3. Display partition information
   

   
   $ sudo fdisk -l /dev/sdb
   Disk /dev/sdb: 15.6 GiB, 16777216000 bytes, 32768000 sectors
   Disk model: VBOX HARDDISK
   Units: sectors of 1 * 512 = 512 bytes
   Sector size (logical/physical): 512 bytes / 512 bytes
   I/O size (minimum/optimal): 512 bytes / 512 bytes
   Disklabel type: gpt
   Disk identifier: 85CF1437-0605-4C91-BE0C-F3B416BEA1D8
   
   Device     Start      End  Sectors  Size Type
   /dev/sdb1   2048 32767966 32765919 15.6G Linux filesystem
   $
   

4. Make the system to re-load the partition tables
   

   
   $ sudo partprobe
   $
   

5. Mount the file system on the partition
   

   
   $ sudo mount -t ext4 /dev/sdb1 /mnt
   $
   

Using gdisk

1. Look up the name the attached harddisk drive using lsblk
2. Create a GPT.
   

   
   $ sudo gdisk /dev/sdb
   GPT fdisk (gdisk) version 1.0.3
   
   Partition table scan:
     MBR: MBR only
     BSD: not present
     APM: not present
     GPT: not present
   
   
   ***************************************************************
   Found invalid GPT and valid MBR; converting MBR to GPT format
   in memory. THIS OPERATION IS POTENTIALLY DESTRUCTIVE! Exit by
   typing 'q' if you don't want to convert your MBR partitions
   to GPT format!
   ***************************************************************
   
   
   Command (? for help): ?
   b       back up GPT data to a file
   c       change a partition's name
   d       delete a partition
   i       show detailed information on a partition
   l       list known partition types
   n       add a new partition
   o       create a new empty GUID partition table (GPT)
   p       print the partition table
   q       quit without saving changes
   r       recovery and transformation options (experts only)
   s       sort partitions
   t       change a partition's type code
   v       verify disk
   w       write table to disk and exit
   x       extra functionality (experts only)
   ?       print this menu
   
   Command (? for help): n
   Partition number (1-128, default 1):
   First sector (34-32767966, default = 2048) or {+-}size{KMGTP}:
   Last sector (2048-32767966, default = 32767966) or {+-}size{KMGTP}:
   Current type is 'Linux filesystem'
   Hex code or GUID (L to show codes, Enter = 8300):
   Changed type of partition to 'Linux filesystem'
   
   Command (? for help): w
   
   Final checks complete. About to write GPT data. THIS WILL OVERWRITE EXISTING
   PARTITIONS!!
   
   Do you want to proceed? (Y/N): y
   OK; writing new GUID partition table (GPT) to /dev/sdb.
   Warning: The kernel is still using the old partition table.
   The new table will be used at the next reboot or after you
   run partprobe(8) or kpartx(8)
   The operation has completed successfully.
   $
   

3. Display partition information
   

   
   $ sudo gdisk -l /dev/sdb
   GPT fdisk (gdisk) version 1.0.3
   
   Partition table scan:
     MBR: protective
     BSD: not present
     APM: not present
     GPT: present
   
   Found valid GPT with protective MBR; using GPT.
   Disk /dev/sdb: 32768000 sectors, 15.6 GiB
   Model: VBOX HARDDISK
   Sector size (logical/physical): 512/512 bytes
   Disk identifier (GUID): 08486B58-59CB-E849-B814-38DD8434D43C
   Partition table holds up to 128 entries
   Main partition table begins at sector 2 and ends at sector 33
   First usable sector is 2048, last usable sector is 32767966
   Partitions will be aligned on 2048-sector boundaries
   Total free space is 0 sectors (0 bytes)
   
   Number  Start (sector)    End (sector)  Size       Code  Name
      1            2048        32767966   15.6 GiB    8300
   $
   

4. Make the system to re-load the partition tables
   

   
   $ sudo partprobe
   $
   

5. Mount the file system on the partition
   

   
   $ sudo mount -t ext4 /dev/sdb1 /mnt
   $
   

Using parted

1. Look up the name the attached harddisk drive using lsblk
2. Create a GPT.
   

   
   $ sudo parted /dev/sdb
   GNU Parted 3.2
   Using /dev/sdb
   Welcome to GNU Parted! Type 'help' to view a list of commands.
   (parted) mklabel gpt
   Warning: The existing disk label on /dev/sdb will be destroyed and all data on
   this disk will be lost. Do you want to continue?
   Yes/No? Yes
   (parted) mkpart primary 1 100%
   (parted) align-check optimal 1
   1 aligned
   (parted) print
   Model: ATA VBOX HARDDISK (scsi)
   Disk /dev/sdb: 16.8GB
   Sector size (logical/physical): 512B/512B
   Partition Table: gpt
   Disk Flags:
   
   Number  Start   End     Size    File system  Name     Flags
    1      1049kB  16.8GB  16.8GB               primary
   
   (parted) quit
   Information: You may need to update /etc/fstab.
   .
   $
   

3. Display partition information
   

   
   $ sudo parted -l /dev/sdb
   ...
   
   
   Model: ATA VBOX HARDDISK (scsi)
   Disk /dev/sdb: 16.8GB
   Sector size (logical/physical): 512B/512B
   Partition Table: gpt
   Disk Flags:
   
   Number  Start   End     Size    File system  Name     Flags
    1      1049kB  16.8GB  16.8GB  ext4         primary
   
   
   $
   

4. Make the system to re-load the partition tables
   

   
   $ sudo partprobe
   $
   

5. Create an ext4 file system on the partition.
   

   
   $ sudo mkfs -t ext4 /dev/sdb1
   mke2fs 1.44.5 (15-Dec-2018)
   /dev/sdb1 contains a ext4 file system
           last mounted on Thu May 28 21:45:35 2020
   Proceed anyway? (y,N) y
   Creating filesystem with 4095488 4k blocks and 1024000 inodes
   Filesystem UUID: 6b43a1a4-ab37-4788-acef-df13149f7bc6
   Superblock backups stored on blocks:
           32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208
   
   Allocating group tables: done
   Writing inode tables: done
   Creating journal (16384 blocks): done
   Writing superblocks and filesystem accounting information: done
   $
   

6. Mount the file system on the partition
   

   
   $ sudo mount -t ext4 /dev/sdb1 /mnt
   $
   

From the above example, we see that parted is a more powerful tool. For instance, it has a
align-check command. This is to check if partition satisfies some alignment constraint.

Mouting File System using UUID

We can mount the file system using its UUID. Below is an example,

1. Display UUID
   
   

   
   $ sudo blkid /dev/sdb1
   /dev/sdb1: UUID="6b43a1a4-ab37-4788-acef-df13149f7bc6" TYPE="ext4" PARTLABEL="primary" PARTUUID="d9b95367-7e63-4789-9b6d-65ef8e7c61c0"
   $
   

2. Mount the file system using its UUID
   
   

   
   $ sudo mount --uuid=6b43a1a4-ab37-4788-acef-df13149f7bc6 /mnt
   $
   

Enabling Serial Console on Debian Linux

I wanted to enable the serial console on a Linux system. The system is a Debian Linux release 10 (a.k.a., "buster"). The official documentation has the following description about the serial console

"

If you are booting with a serial console, generally the kernel will autodetect this. If you have a videocard (framebuffer) and a keyboard also attached to the computer which you wish to boot via serial console, you may have to pass the console=device argument to the kernel, where device is your serial device, which is usually something like ttyS0. 

You may need to specify parameters for the serial port, such as speed and parity, for instance console=ttyS0,9600n8; other typical speeds may be 57600 or 115200. Be sure to specify this option after “---”, so that it is copied into the bootloader configuration for the installed system (if supported by the installer for the bootloader). 

In order to ensure the terminal type used by the installer matches your terminal emulator, the parameter TERM=type can be added. Note that the installer only supports the following terminal types: linux, bterm, ansi, vt102 and dumb. The default for serial console in debian-installer is vt102. If you are using an IPMI console, or a virtualization tool which does not provide conversion into such terminals types itself, e.g. QEMU/KVM, you can start it inside a screen session. That will indeed perform translation into the screen terminal type, which is very close to vt102.

"

It also states,

"

Those used to change inittab to enable/disable virtual or serial consoles will notice that that file is gone from clean installs. This is all managed through systemd directly now. For example, you can enable a serial console on COM1 with: 

systemctl enable serial-getty@ttyS0.service
systemctl start serial-getty@ttyS0.service

However, it is generally preferable to add console=ttyS0 on the kernel commandline, since this also enables kernel output on reboots. This is done by adding the following to /etc/default/grub: 

GRUB_CMDLINE_LINUX="console=ttyS0"

... and running update-grub. This will take effect only on the next reboot, however.

"

It is clearly that the documentation offers two solutions, using the systemd service or using the boot parameter. Perhaps, the former has the shortcoming that the serial console may not start if the systemd does not get a chance to run because we happen to have a boot problem. The preferred method, as suggested is to pass a boot parameter to the kernel. Since I have the grub boot loader installed, this becomes a simple two step approach,

1. Edit /etc/default/grub file. In my case, replace

   
   GRUB_CMDLINE_LINUX_DEFAULT="quiet"
   

   
   by

   
   GRUB_CMDLINE_LINUX_DEFAULT="console=ttyS0 console=tty0"
   

   
   
2. Update the grub.cfg file

   
   update-grub -o /boot/grub/grub.cfg
   

I happened to back up the old grub.cfg file. By comparing the old and new grub.cfg file, we can easily see the difference between the two files,

$ diff /boot/grub/grub.cfg /boot/grub/grub.cfg.bu01
diff /boot/grub/grub.cfg /boot/grub/grub.cfg.bu01
119c119
<       linux   /boot/vmlinuz-4.19.0-8-686 root=UUID=123456789 ro  console=ttyS0 console=tty0
---
>       linux   /boot/vmlinuz-4.19.0-8-686 root=UUID=123456789 ro  quiet
137c137
<               linux   /boot/vmlinuz-4.19.0-8-686 root=UUID=123456789 ro  console=ttyS0 console=tty0
---
>               linux   /boot/vmlinuz-4.19.0-8-686 root=UUID=123456789 ro  quiet
$