I still have this box

I still have this box. And the errata is still available. And this is not RHEL 4.x from 2004. It's from 1997.

Red Hat 4.1 (front)

More images here, here, here, here and here. One curious detail from the user's guide:

Red Hat 4.1 (desktop)


Uploading firmware to Arduino Mega 2560 using avrdude in OpenBSD

For those who develop firmware for Arduino, OpenBSD provides a CLI interface to do it in its ports system. It's an alternative way to it, faster and you do not have to rely on the crap default Arduino IDE, which pleasures new users but do not attract more advanced users which are used to more powerful editors.

When you run arduinoproject to bootstrap a new project, it gives you a Makefile file that you have to tweak to fit your board. pkg-readmes, doc which come included in the package, recommends you to check /usr/local/share/arduino/boards.txt and then set Makefile. It's not always obvious, and now and then I have to revisit a note I kept somewhere.

UPLOAD_RATE = 115200
PORT = /dev/cuaU0
MCU = atmega2560
F_CPU = 16000000
VARIANT = mega

The detail here is that you have to add a -D flag to the AVRDUDE_FLAGS. If you do not do this, you may get the following:

$ sudo make upload                        
/usr/local/bin/avrdude -V -F -C /etc/avrdude.conf -p atmega2560 -P /dev/cuaU0  -c stk500v2 -b 115200 -U flash:w:applet/blink.hex

avrdude: AVR device initialized and ready to accept instructions

Reading | ################################################## | 100% 0.01s

avrdude: Device signature = 0x1e9801
avrdude: NOTE: FLASH memory has been specified, an erase cycle will be performed
         To disable this feature, specify the -D option.
avrdude: erasing chip
avrdude: stk500v2_command(): command failed

avrdude done.  Thank you.

*** Error 255 in /home/dbolgheroni/bghbox/electronics/arduino/blink (Makefile:222 'upload')

Didn't investigate if it's the correct-way-to-do-it, but I'll do this later to send a patch to the project. Maybe it's time to update the port to Arduino 1.5, or to update the examples which comes included in Makefile to reflect the most common boards used today (e.g. UNO).

Try to upload again and you're done.

BB e Java em distro Debian-based


A última mudança do sistema do Banco do Brasil quebrou quem utiliza um sistema que não seja Windows, seja Linux, OpenBSD, Mac ou outros. No entanto, em distros Debian-based (Ubuntu, Linux Mint, entre outros), existe uma solução relativamente simples:

$ sudo add-apt-repository ppa:webupd8team/java
$ sudo apt-get update
$ sudo apt-get install oracle-java7-set-default

Existem diferentes implementações de Java, como OpenJDK, Oracle Java, IBM Java, etc. A "oficial" é a da Oracle (antiga Sun), mas a maioria das distros utiliza como default a OpenJDK, justamente por ser open source. Trocar a OpenJDK pela Oracle Java não deveria ser necessário, e pode quebrar outras aplicações, mas resolve o problema.

Using an USB flash drive to boot OpenBSD/macppc

I have an iMac G3. It's old. I like it. More than once, I screwed up the OS and had to install again.

You have more than one way to do it. You can boot from a CD-ROM, but mine is broken, as most of the CD-ROMs drives on dated machines. Or boot from the network, but you have to setup the environment. Or boot from an USB flash drive, which I didn't think it was possible until I tried a few days ago.

There are some discussions about how to correctly create a bootable USB install media for OpenBSD. Recently, Chris Cappuccio announced the availability of images ready to be copied to an USB flash drive, but they are for i386 and amd64 ports only.

One way which is very debatable on how to do this is to dd the ISO image directly to the USB flash drive. Not because it doesn't work, but because it may not work on all systems. A .iso, more specifically an ISO 9660 .iso file, is a filesystem suited for optical discs, not USB flash drives. Some firmwares (IBM PC BIOS, Open Firmware) will see them as a disk, but you can't be so sure about this. However, this is not the only problem. If you want to dig about the concerns raised on the mailing lists, you can check the archives here and here.

What I'm putting up here is not what you should do, but instead what have worked for me. It's a Reminder For Myself. OpenBSD team is very rigorous about the project documentation, and what's stated at the INSTALLATION NOTES for OpenBSD/macppc 5.6 should be applicable to all supported machines, not just my case as I'm doing here. So, if you read it here, or any other blog for that matter, don't ask it on the mailing lists. Refer to the official FAQ. Refer to the man pages. If you don't find what you're looking for on these references, then yes, ask on one of the mailing lists.

At the time of this writing, the latest version of OpenBSD is 5.6. So, download the cd56.iso from your preferred mirror:

$ ftp ftp://ftp.openbsd.org/pub/OpenBSD/5.6/macppc/cd56.iso

dd'it to your USB flash drive:

# dd if=cd56.iso of=/dev/sd1c bs=4k

To check, in Open Firmware, at some point you'll see something like this:

0 > dev / ls
ff909748: /pci@f2000000
ff926b98:   /usb@18
ff947668:     /disk@0
ff92e820:   /usb@19
ff947288:     /keyboard@1
0 >

If you remove the USB install media, you'll note that this turns out to something like this:

0 > dev / ls
ff909748: /pci@f2000000
ff926b98:   /usb@18
ff92e820:   /usb@19
ff947288:     /keyboard@1
0 >

Notice that the disk just below /usb@18 gone. Of course, this can vary depending on the model of your machine, the Open Firmware version, etc, but nonetheless it will be very similar. And you don't need the whole path to indicate from where to boot. You can use the devalias command for this:

0 > devalias
usb0                /pci@2f000000/usb@18
0 >

To boot:

0 > boot usb0/disk@1:,\ofwboot

boot> boot 5.6/macppc/bsd.rd

Also note that cd56.iso doesn't have a bsd.rd right at the root, so you need to specify the path to it. Now install OpenBSD/macppc almost as equal to any platform.

Parameters, Arguments and Options

There is a confusing concept about each one. You use this all the time, you know exactly how they work, but until the moment to try to write about it, you get asking yourself: "parameter or argument"? To this list, I added options too. Why? Because parameter is often used when you are reading man pages.

You can read the differences between then in Wikipedia or in other places, but I'll try a simpler, more visual approach. There are two main contexts where you use these terms: in 1) programming and in 2) command-line interface.

Programming Context

  • (formal) parameter: is the variable in a function definition or in a prototype declaration, and is used to denote type. Example:

    /* function definition, so a and b are parameters */
    int func(int a, int b) { ... }
  • (actual) argument: is the value or expression in a function call, and is used to denote an instance. Example:

    /* this is a function call, 3 and (x + y) are arguments */
    func(3, x + y);

Command-line Interface Context

In this context, the terms CLI argument or parameter are used interchangeably. The intent is to detail some terminology, not all possibilities, such as --longoptions and other combinations. Take for example the following:

    $ cmd -xarg something
  • -x is an option, called also switch or flag, which is a parameter/CLI (command-line interface) argument
  • -xarg (or -x arg) is an option plus its option argument (sometimes optional), which is a parameter/CLI argument
  • something is a parameter/CLI argument
  • -xarg something (the whole thing after cmd) is also a parameter/CLI argument

It's a logic exercise.