Μηνιαία αρχεία: Νοέμβριος 2016

ATEN – USB-to-Serial Converter (35cm) UC232A – Windows 10 (64bit) Drivers

 στο Windows  επισημασμένο με ετικέτα ATEN / Converter / Drivers / serial / UC232A / usb / Windows 10 Από

Background

Recently we started using the UC232A USB-to-Serial Converter to connect to a board.
The software we used was TeraTerm on a 64bit Windows 10 without installing custom drivers.

Our serial port configuration was the following:

  • Baud rate: 115200
  • Data: 8 bit
  • Parity: none
  • Stop: 1 bit
  • Flow control: none
  • Transmit delay:
    5 msec/char
    5 msec/line

The problem

We noticed that something was wrong with the process as the terminal would not operate consistently.
Some times keystrokes did not appear on screen, in other times results would not appear correctly (they could be truncated or mixed with other data) and in general, the system acted like it was possessed by a ghost.

Troubleshooting

We played around with the configuration parameters, hoping that it was an issue like having the need to add large transmit delay but it did not change anything, the communication with the board was unstable.
Afterwards, we switched to another cable, of a different company, and everything worked as expected. The data on the screen was consistent and the ghost was banished. The UC232A was brand new so we tested that it works on a GNU/Linux machine, which turned out to be OK. Doing so, these two tests led us to the conclusion that since both the cable operates properly on GNU/Linux and the board operates properly using the other cable, that the issue we had was the automatically installed Windows 10 drivers.

Solution

While the cable was unplugged, we installed the official drivers we found here.
To find the drivers on that page, click on Support and Download tab at the bottom and then click on the Software & Drivers panel.
From the new table that will appear, under the category Windows Legacy Software & Driver we used the latest version that was available at the time that this post was written, which was v1.0.082 dated 2016-01-27 uc232a_windows_setup_v1.0.082.zip ([download id=”2357″] retrieved on the 23rd of November 2016).
After the download was finished, we restarted the machine, plugged in the cable and gave it another go.
The system was working as expected.

Following, you will find the screenshots from the device manager, after we got the cable working right.

uc232a-device-manager

uc232a-device-properties

uc232a-drive-file-details

Reclaim empty space from VirtualBox VDI disk images by shrinking

 στο Windows  επισημασμένο με ετικέτα VBoxManage / VDI / virtualbox / zerofree Από

Recently, we did some cleanup in certain GNU/Linux virtual machines, where we hoped that VirtualBox would release the disk space that is not used and shrink the size of the VDI files.
Unfortunately, that did not happen even after freeing more than 100GB of space from the guest machine.

We did manage though to reclaim the empty space manually, using the zerofree and VBoxManage utilities.

Following is the guide we followed to do so:

Part 1: Clean-up the guest machine using zerofree

We needed to find the unallocated, blocks with non-zero value content in the ext2, ext3 or ext4 filesystem (e.g. /dev/sda1) and fill them with zeroes.
Since the filesystem has to be unmounted or mounted as read-only for zerofree to work, we decided to use a Live CD to complete this task as it would be the simplest solution to follow.

Step 1: Download SystemRescueCd Live Image

We downloaded the SystemRescueCd Live Image and inserted it to the guest machine as a Live CD.

Step 2: Identify partitions and disks using fdisk -l

We booted the virtual machine from the Live CD, when the terminal appeared, we typed fdisk -l to see all available disks and partitions.

Depending on your configuration you will see the following

If you performed your installation using standard partition

Disk /dev/sda: 200 GiB, 214748364800 bytes, 419430400 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: 0x64af3527

Device     Boot     Start       End   Sectors  Size Id Type
/dev/sda1  *         2048 411043839 411041792  196G 83 Linux
/dev/sda2       411045886 419428351   8382466    4G  5 Extended
/dev/sda5       411045888 419428351   8382464    4G 82 Linux swap / Solaris

or if you performed your installation using LVM

Disk /dev/sda: 214.7 GB, 214748364800 bytes, 419430400 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
Disk label type: dos
Disk identifier: 0x000523ce

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048     1026047      512000   83  Linux
/dev/sda2         1026048   419430399   209202176   8e  Linux LVM

Disk /dev/mapper/centos-root: 53.7 GB, 53687091200 bytes, 104857600 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


Disk /dev/mapper/centos-swap: 4160 MB, 4160749568 bytes, 8126464 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


Disk /dev/mapper/centos-home: 156.3 GB, 156304932864 bytes, 305283072 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

From the above results, we keep the paths to the real partitions and the paths to the LVM partitions, e.g.
/dev/sda1 which is 196GB, /dev/mapper/centos-home and /dev/mapper/centos-root

Step 3: Perform the cleanup

To perform the clean up, execute for each of the above paths the command zerofree, e.g.

zerofree /dev/sda1;
zerofree /dev/mapper/centos-home;
zerofree /dev/mapper/centos-root;

Give it some time to complete the task, the larger the partition, the more the time it will take.

Part 2: Shrink the guest machine disk images using VBoxManage

We used VBoxManage with the parameter --compact, which it is used to compact disk images, i.e. remove blocks that only contains zeroes. It shrinks dynamically allocated images by reducing the physical size of the image without affecting the logical size of the virtual disk. Compaction works both for base images and for diff images created as part of a snapshot. For this operation to be effective, it is required that free space in the guest system first be zeroed out and that is why we had to perform Step 1 using zerofree before.
Please note that compacting is currently only available for VDI images.

To use, just issue the command "C:\Program Files\Oracle\VirtualBox\VBoxManage.exe" modifyhd --compact <DISK_PATH> pointing to the disk you just cleaned up using zerofree
Please note that the virtual machine should be stopped before starting this operation.

Press the key combination Win + R to pop up the Run prompt.
Type cmd in the input box and hit the Enter key.

"C:\Program Files\Oracle\VirtualBox\VBoxManage.exe" modifyhd --compact "F:\Ubuntu\Ubuntu.vdi"
"C:\Program Files\Oracle\VirtualBox\VBoxManage.exe" modifyhd --compact "C:\Users\bytefreaks\VirtualBox VMs\CentOS\CentOS.vdi"

Downgrade GNU patch on CentOS 7.0 (64bit) to version 2.6.1

 στο GNU/Linux  επισημασμένο με ετικέτα CentOS / downgrade / patch Από

Recently we had to download GNU patch from version 2.7.1 to any version less than version 2.7 series.
We used patch version 2.6.1 which is the latest in the version 2.6 series.

We were trying to compile Linux Kernel 3.0.35 source code with some custom patches.
While applying the patches we got the following errors:

File firmware/imx/sdma/sdma-imx25-to1.bin: git binary diffs are not supported.
File firmware/imx/sdma/sdma-imx31-to1.bin: git binary diffs are not supported.
File firmware/imx/sdma/sdma-imx31-to2.bin: git binary diffs are not supported.
File firmware/imx/sdma/sdma-imx35-to1.bin: git binary diffs are not supported.
File firmware/imx/sdma/sdma-imx35-to2.bin: git binary diffs are not supported.
File firmware/imx/sdma/sdma-imx50-to1.bin: git binary diffs are not supported.
File firmware/imx/sdma/sdma-imx51-to3.bin: git binary diffs are not supported.
File firmware/imx/sdma/sdma-imx53-to1.bin: git binary diffs are not supported.

Apparently, version 2.7 does not support binary diffs.
We can verify this claim from the release announcement.

Support for most features of the “diff –git” format, including renames and copies, permission changes, and symlink diffs. Binary diffs are not supported yet; patch will complain and skip them.

Methodology


#Making sure we are not missing any 32bit libraries since we are on a 64bit machine
yum install glibc.i686 ncurses-libs.i686;
#Download the source code
wget ftp://ftp.gnu.org/gnu/patch/patch-2.6.1.tar.gz;
#Extract the files
tar -zxf patch-2.6.1.tar.gz;
#Navigate to the folder
cd patch-2.6.1;
#Configure the installation and make all necessary checks
./configure;
#Build
make;
#Remove existing version
sudo yum remove patch -y;
#Install
sudo make install;

How to suppress binary files from matching results

 στο GNU/Linux  επισημασμένο με ετικέτα binary / exclude / find / grep Από

When you try to find all files that contain a certain string value, it can be very costly to check binary files that you might not want to check.
To automatically prevent your search from testing if the binary files contain the needle you can add the parameter -I (capital i) to prevent grep from testing them.
Using grep, -I will process a binary file as if it did not contain matching data, this is equivalent to the --binary-files=without-match option.

Example

find . -type f -exec grep 'string' '{}' -s -l -I \;

The above command breaks down as follows:

  • find . -type f Find all files in current directory.
  • -exec For each match execute the following.
  • grep 'string' '{}' Search the matched file '{}' if it contains the value ‘string’.
  • -s Suppress error messages about nonexistent or unreadable files.
  • -l (lambda lower case) or --files-with-matches Suppress normal output, instead print the name of each input file from which output would normally have been printed. The scanning will stop on the first match.
  • -I (i capital) or --binary-files=without-match Process a binary file as if it did not contain matching data.