[Wed Oct 18 15:53:30 CDT 2017]

I just ran into an issue while trying to mount a FreeDOS .img file in Linux. Using the regular command to mount via the loopback device wouldn't work:

# file filename.img 
filename.img: DOS/MBR boot sector; partition 1 : ID=0x6, active, start-CHS \
(0x0,1,1), end-CHS (0x7,254,63), startsector 63, 128457 sectors

# mount -o loop file.img /mnt/usb
mount: wrong fs type, bad option, bad superblock on /dev/loop6,
       missing codepage or helper program, or other error

       In some cases useful info is found in syslog - try
       dmesg | tail or so.

The key is that this is the image of a disk, and not the image of a partition. Therefore, we need to find out at which point the actual partition begins, and then pass it as an offset to the mount command:

# fdisk -l filename.img
Disk filename.img: 62.8 MiB, 65802240 bytes, 128520 sectors
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: dos
Disk identifier: 0x00000000

Device                                              Boot Start    End Sectors  Size Id Type
filename.img1                                       *       63 128519  128457 62.7M  6 FAT16

# echo "63*512" | bc -l
32256

# mount -t msdos -o loop,offset=32256 filename.img /mnt/usb/

And voila! That does it. {link to this entry}

[Wed Oct 18 11:24:11 CDT 2017]

Someone asked me why I had recommended to run the Linux kernel with the nohz=off option. Actually, the question was about the parameter and what it does. As it happens so often, Stack Overflow to the rescue. Basically, the so-called "tickless kernel" feature (i.e., nohz=on) reduces power consumption by allowing processors that are sitting on idle to continue in that state, instead of periodically waking up as it used to be the case in older kernels. However, nice as this may be for power consumption, it also has a performance penalty associated with it. So, in those cases, one is better off configuring nohz=off as a kernel boot option. {link to this entry}

[Tue Oct 3 15:38:14 CDT 2017]

Here is a useful cheatsheet with the GNOME keyboard shortcuts. A shortcut that I wasn't aware of that I find quite useful is this to switch the keyboard focus to the top bar:

Ctrl + Alt + Tab

Once there, you can easily access any of the elements from the top bar using your keyboard. {link to this entry}