To debug the printing problem and to add another, better layer, . . . → Read More: Timestamp in Linux using ftime for millisecond timing]]> I am working on an embedded project at the moment that prints debug messages to a serial console.  Interestingly, it seems that some of the prints are arriving out order from the actual flow of the software when they originate from the same thread.

To debug the printing problem and to add another, better layer, of debugging to the project I added a time stamp to a preprocessor definition for the existing printf() macro.

Here is the existing print macro:

#define debug_print(fmt, arg)          printf (fmt, arg)

To add a time stamp we need to use the timeb struct from sys/timeb.h.  Since a struct is used, we need to give it a focus. Otherwise we’ll get compile errors. It will need to be put in a false do while loop.

#define debug_print(fmt, arg) \
  do { \
    struct timeb tp; \
    ftime(&tp); \
    printf("%ld.%d: " fmt, tp.time, tp.millitm, arg); \
  } while (0)

Now, in your program you need to make sure sys/timeb.h is added and then use the new print macro.

#include <stdio.h>
#include <sys/timeb.h>

#define debug_print(fmt, arg) \
  do { \
    struct timeb tp; \
    ftime(&tp); \
    printf("%ld.%d: " fmt, tp.time, tp.millitm, arg); \
  } while (0)

int main() {
  while(1) {
    debug_print("This is dbg print and a number: %d\n", 10);
    usleep(10000);
  }
  return 0;
}

Enjoy!

Let’s take a look at Knoppix. It is one of the most popular Live CD’s. In the CD structure of Knoppix there is a file that contains the root file system . . . → Read More: Using cloop in FreeBSD]]> There are lots of Linux distributions that have a ‘Live CD’ that allow you to rescue your system or try before you bu… install.

Let’s take a look at Knoppix. It is one of the most popular Live CD’s. In the CD structure of Knoppix there is a file that contains the root file system (rootfs). That file is a cloop image file. Each block is compressed individually which allows decompression on the fly or at a specific point in the file.

This allows a rootfs to be about 1 GB in actual size but compressed it will fit into about 700 MB.

When a system boots from this CD [image], a kernel loads the cloop device and then opens the rootfs cloop file. Viola! The root file system is loaded into a ramdisk and is accessible as if it was an installed distribution.

This is great for Linux – not so great for FreeBSD. There are many Linux only or FreeBSD only file types and differences that make using the two systems on the same network very difficult.

I prefer FreeBSD because of its sheer solidness. It’s like comparing a car that uses a gasoline engine (Linux) versus a diesel engine (BSD). Linux is the new hot-ness; fast, sleek, portable, adaptable, pump-n-go. FreeBSD is like the 80s era of cars; cast aside because they aren’t sexy, requires the right glow plugs, needs patience, but it will run on any thing that has enough compression and it will go forever.

By default, FreeBSD lacks the ability to mount cloop images. Luckily, Klaus Knopper wrote a FreeBSD module that allows mounting of a cloop image. This allows someone that uses FreeBSD to modify a cloop image with out needing a Linux box.

To install the cloop module for FreeBSD, build and install the cloop-utils.

# cd /usr/ports/sysutils/cloop-utils/
# make && make install

Now to mount the cloop image.

In this example I am using Damn Small Linux tftpboot.

# unzip dsl-1.5-tftpboot.zip

# gunzip minirt24.gz

# mdconfig –a –t vnode –f minirt24

# mount –t ext2fs /dev/md0 /mnt/dsl

#kldload geom_uzip

# mdconfig –a –t vnode –f /mnt/dsl/cdrom/KNOPPIX/KNOPPIX

# mount –t cd9660 /dev/md1.uzip /dev/dslcdrom

Now you should have access to the cloop ‘KNOPPIX’ root file system in /mnt/dslcdrom. Follow the steps in reverse to close and re-zip the files I my case, it allows me to update any part of the rootfs from the PXE server which is not Linux.

My iPod mini did just that Friday evening. It had a good life from 8th June 2005 until 16th February 2007. Of course, I’m pretty sure that I was the direct cause of its demise.

I had the mini . . . → Read More: Dead iPod]]> It really sucks when all of a sudden your digital music player just goes belly up.

My iPod mini did just that Friday evening. It had a good life from 8th June 2005 until 16th February 2007. Of course, I’m pretty sure that I was the direct cause of its demise.

I had the mini in my back pocket and I sat down. The hold switch was activated so that the key press wouldn’t stop the music. When I removed the mini from my pocket, the forward and play/pause buttons where stuck in the ‘pressed’ position. It seemed that the buttons were caught on the aluminum case. I gently taped the mini on my desk to un-stick the buttons. Worked great; the buttons returned to their normal position.

Shortly after, the mini began to skip through all the songs. No problem I thought, I’ll just reboot it. As soon as I pressed the select and menu button, the mini reset and displayed a ‘sad iPod‘ icon. And I could hear what sounded like hard drive heads clicking. All this time I have always though that my iPod mini was a flash based player. Apparently, it’s has a Microdrive in it.

After disassembling my iPod mini, I removed the Microdrive(R) and replaced it with a 1 GB CF memory card that I was planning on using for another project. The CF card was going to be used for ZeroShell. Oh well.

Once the Microdrive(R) was replaced with the CF memory card I had to put the mini into disk mode to reformat the ‘drive’ using an iPod Updater (it was not the latest and greatest but it worked perfectly). Once the update was complete, I reset the iPod again and started iTunes. When iTunes finally loaded, it asked what I wanted to name the iPod and informed me that my entire music library wasn’t going to fit on the device (which was down to 1GB from 4GB).

Changing the mini from a Microdrive(R) to flash really increased the update speed. After a few minutes, iTunes had loaded as much audio onto the mini as it could fit.

When I was disassembling the mini, I managed to scratch the select button on the touch pad and mauled the aluminum case. Since it still works, I’m not that upset about it.

UPDATE:

30 June 2007 – I’ve updated my iPod with a pqi 8GB CF. iTunes 7 will restore the firmware/format on the new disk which makes the iPod updater obsolete.

A long time ago, my father showed me how to forward X applications from another system to my localhost with Cygwin.

Unfortunately, between that time and now, I had forgotten what he had showed me.

So, as a reminder for myself, here’s how:

The classic . . . → Read More: X forwarding – my reminder]]> Every once and a while, I have a brain lapse.

A long time ago, my father showed me how to forward X applications from another system to my localhost with Cygwin.

Unfortunately, between that time and now, I had forgotten what he had showed me.

So, as a reminder for myself, here’s how:

The classic is assumed here:

• Cygwin is installed with X.
• Putty
• Remote system with X utilities

On the localhost:
Start Cygwin then type

$ X -multiwindow &
$ export DISPLAY=127.0.0.1:0.0

Start putty:

Under Connection -> SSH -> X11 -> Forwarding
Check the ‘Enable X11 forwarding’
In the ‘X display location’, enter:
127.0.0.1:0.0

Open the connection to the remote host as normal from this point.
Once logged in, you can now open your X apps from the server

$ gschem

Unlike other OSes that I have used, Slackware has an awesome ‘autoraid’ capability that is idiot proof. . . . → Read More: Making RAID array in Slackware (because it’s easy as pie!)]]> Let’s say that you needed to store a large amount of data in a central location (I.E. directory) but the largest drive that you can afford and find for a reasonable price is a 400GB Seagate SATA drive.

Unlike other OSes that I have used, Slackware has an awesome ‘autoraid’ capability that is idiot proof. Believe me! I’m not only the president, I’m also a client!

In four easy steps you too can have a RAID 0, 1, or 5 setup.

Step 1: Use fdisk to prepare the disk

# fdisk /dev/sda # sd just happens to be the SCSI/SATA controller on my system

Disk /dev/sda: 400.0 GB, 400088457216 bytes

255 heads, 63 sectors/track, 48641 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
Command (m for help): n

Command action

e extended
p primary partition (1-4)
p
Partition number (1-4): 1
First cylinder (1-48641, default 1):
Using default value 1
Last cylinder or +size or +sizeM or +sizeK (1-48641, default 48641):
Using default value 48641

Command (m for help): t
Selected partition 1
Hex code (type L to list codes): fd #fd is “Linux raid auto�?
Changed system type of partition 1 to fd (Linux raid autodetect)

Repeat the same step for each drive.

Step 2: Creating the configuration file

Edit or create the file /etc/raidtab with the following content

raiddev /dev/md0
raid-level 0
nr-raid-disks 2
nr-spare-disks 0
persistent-superblock 1
chunk-size 128
device /dev/sda1
raid-disk 0
device /dev/sdb1
raid-disk 1

# repeat for each ‘raid’ disk:

# device /dev/xdaz
# raid-disk n

Step 3: Making the RAID

# mkraid /dev/md0

Step 4: Formatting the new RAID device

# mkfs.reiserfs /dev/md0

Be sure to add the /dev/md0 device to your fstab so it will mount the next time the system reboots.