Categoria: Informatica

L’informatica e la tecnologia sono la mia passione. Trasformare la passione in lavoro non sempre è un bene. A volte si finisce per odia la propria passione. Per evitarlo, dopo alcuni anni di lavoro, mi sono sposato verso tematiche di governance dei progetti. Questo mi ha consentito di mantenere integra “quasi” la mia passione e di divertirmi sul lavoro perché lambisco la mia passione.

Le tematiche che affronto per passione sono molto varie, a volte mi ritrovo ad affrontar elo stessa tema da capo a distanza di tempo e mi accordo di aver dimenticato qunto appreso al primo giro. Succede quindi che rifaccio lo stesso percorso di apprindimento. Per evitarlo metto qui i miei appunti.

 

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TBS driver new try

Sometime I try to make the fuc…. TDB 6022 card working on linux without making the other card out of work.

Yesterday I tried to build the TBS saa716x driver against the newest linux media, after patching a little bit everything compiles fine the remote works but the TBS6922 frontend which is already compiled in the TBS distribution generates a kernel oops.

Today I tried the other way, I entirely removed the CX23885 from the TBS tree and replace it with the one found in the latest media_build tree. The result was worst, I couldn’t even build the driver because the media_tree used by TBS developers is really tooooooo old. Kernel_version.h reports version

#define V4L2_VERSION 196608

which corresponds to a very very very very old media_tree linux-media-2011-05-31.tar.bz2

So for me by now no way to make the new cards using CX23885 working with the TBS 6922 card, so the brand new TBS6922 card remains off.

I’m still hoping to get and answer from TBS developers….

 

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Wake on Wan with DSL-2740B

Using wake on lan is quite simple, trying to use it from internet requires some extra attention.When you use WOL you send a broadcast packet to your modem/router and the modem /router propagates this broadcast packet to all Ethernet connected devices.

To send a WOL packet from internet been sure this packet arrives to your modem through internet you have to set the IP without broadcast.When the packed reaches the modem the modem tries to deliver the packet with the mac-address to a connected device using the routing tables.The routing table tells the modem to forward every packet from port 9 (the port usually used for WOL) to your workstation (this is because you previously set up the routing table.) So for example your packet should be sent to workstatio with ip 192.168.1.2. But your workstation is off line and so the router doesn’t know where IP 192.168.1.2 is.
How con you tell the modem that 192.168.1.2 is connected?

This job is done by the ARP (Address Lookup Table) of your modem, but the table is empty if your workstation is offline for a while or if your modem clears periodically the ARP table.

To add the missing entry in the ARP table you have to signin to your modem using telnet and from there you have to type this command using the right parameters:

arp add 192.168.1.2 11:22:33:44:55:66

Now you can send a WOL from internet and your workstation should wake up correctly.

 

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Enable/disable jounal on running ext root partition

Some times ago, trying to reach better performances on my SDD, I followed the wrong suggestion to disable the journal. This solution isn’t really good because I had some data loss and at almost each reboot the system got in fsck.

Yesterday I decided to go back and restore the journal. Each guide I found online was related to non root fs or to boot in maintenance mode. The only thing you need is a ro mountetd fs and usually you fine on internet this command line:

sudo mount -r -o remount /

Which is not enought and you get a busy error message.

The way to go around this issue is to force the remount, so if you want to enable journal:

sudo mount -f -r -o remount /dev/sda6

sudo tune2fs -O has_journal /dev/sda6

Or disable it:

sudo mount -f -r -o remount /dev/sda6

sudo tune2fs -O has_journal /dev/sda6

 

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Barcode recognition

E’ dai tempi in cui lavoravo come senior ECMS Consultant, una società specializzata nei processi documentali, che non mi cimentavo con il riconoscimento dei codici a barre da documenti acquisiti via scanner.

Devo dire che da allora i passi avanti sono stati notevoli, sia per la varietà di codici a barre e matrixcode disponibili rispetto un tempo (soprattutto matrixcode), che per le tecniche e i software disponibili per il riconoscimento.

Kofax, già hai tempi leader di mercato, ha mantenuto una posizione nettamente dominante, ma oggi sono disponibili alternative low cost, con licenze di varia natura. Una libreria nota di merito è sicuramente ZXING in grado elaborare i seguenti formati:

    • UPC-A and UPC-E
    • EAN-8 and EAN-13
    • Code 39
    • Code 128
    • ITF
    • Code 93
    • Codabar
    • RSS-14 (all variants)
    • RSS Expanded (most variants)
    • Data Matrix
    • Aztec (‘beta’ quality)
    • PDF 417 (‘alpha’ quality)

Da un primo test empirico su un numero limitato di documenti riesce a tenere testa ai concorrenti e con codici a barre code 128 acquisiti a 300Dpi a tasso di riconoscimento prossimo al 100%.