Category: Linux

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Linux C++ IDE; NX

Lately, I’ve been developing on Linux. When developing remotely, I can get
along with a shell and vim, with VNC, or with remote-X. However, none of these
options are as fast or as nice as using NX. Here are the instructions to install and use
the NX server and client on Fedora Core 5 and 6:
http://fedoranews.org/contributors/rick_stout/freenx/

What’s the best C++ IDE in Linux? Out of the three IDEs I have evaluated, I’d
recommend either SlickEdit or NetBeans C++. I haven’t tried Emacs. I’ve installed KDevelop, but haven’t tried it much yet.

Eclipse CDT

  Overall: Immature and over complicated. I prefer vim with a ctags file, jedit, nedit, or gedit.
  Code Completion: Broken -- rarely works
  Search by Symbol or Reference: Broken
  Debugger support: Yes. Ugly user interface
  Custom build (bjam): Yes
  Project support: Yes. Automatically adds new files, removes old files from workspace
  Refactoring support: No
  Subversion support: Yes, with plugin

SlickEdit

  Overall: Excellent IDE
  Code Completion: The best of the bunch, but not as good as Visual Studio
  Search by Symbol or Reference: Excellent
  Debugger support: Yes. Difficult to setup
  Custom build (bjam): Yes
  Project support: Yes
  Refactoring support: Good
  Subversion support: Yes
  Notes: Has fairly good key emulation support for Visual Studio, Vim, Brief, Emacs, etc.
  Language Support: Tagging and syntax highlighting for C++, Java, Perl, Python and Ruby (to name just a few).

NetBeans C++

  Overall: Better than Eclipse CDT
  Code Completion: Yes
  Search by Symbol or Reference: Yes
  Debugger support: Yes, but haven't yet figured out how to set breakpoints.
  Custom build (bjam): Yes
  Project support: Not yet evaluated
  Refactoring support: No
  Subversion support: Yes, with plugin or with NetBeans beta 6.0.

KDevelop

  Overall: Not yet evaluated
  Code Completion: Yes
  Search by Symbol or Reference: Symbol - Yes (using ctags); Reference - Unknown.
  Debugger support: Yes
  Custom build (bjam): Most likely
  Project support: Yes
  Refactoring support: Unknown
  Subversion support: Yes

None of these tools are as good at code completion as Microsoft Visual Studio 2005.

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Fedora Core 6 Disk Encryption

Here’s how to set up an encrypted disk and swap partition on Fedora 6. Refer to Disk encryption in Fedora: Past, present and future for more information. For RedHat (RHEL 4) or CentOS 4, refer to http://wiki.centos.org/TipsAndTricks/EncryptedFilesystem.

Warning: I have no idea how to set up encrypted disks in combination with LVM. I tend to shy away from LVM because it’s yet another layer of abstraction, making it difficult to recover a broken system. However, the following links may be of help: [1], [2].

In these examples, I’m encrypting the /home partition located on partition /dev/sda5, and the swap partition located on /dev/sda3. The partitions will be different on your system.

Create and Format Encrypted Disk

Before you start, you may want to obliterate the partition that will hold the encypted file system:

$ shred /dev/sda5

Setup the crypt disk:

$ cryptsetup -y --cipher aes-cbc-essiv:sha256 --key-size 256 luksFormat
/dev/sda5
  # You must type "YES" to proceed
  # It will prompt you for a passphrase twice
$ cryptsetup luksOpen /dev/sda5 home
$ mkfs.ext3 -L /home /dev/mapper/home
$ cryptsetup luksClose home

Create /etc/crypttab

Create the /etc/crypttab file. It should be formatted as follows:

swap    /dev/sda3       /dev/urandom swap,cipher=aes-cbc-essiv:sha256
home    /dev/sda5       none    luks

Edit /etc/fstab 

/dev/mapper/home        /home                   ext3    defaults 2 1
/dev/mapper/swap        swap                    swap    defaults 0 0

Whenever you boot the system, it will prompt you for your passphrase for the /home partition.

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Linux, Asus M2V, Attansic Ethernet and SATA hard drive problems.

At work, I got a shiny new Linux development machine — And AMD 64 Dual Core 3800+ processor running on an Asus M2V 1.xx motherboard.

After installing Fedora Core 6, I ran into two problems. First, the built-in Attansic L1 Ethernet adapter wasn’t recognized. Google research revealed that an Attansic L1 driver will probably appear in the mainline Linux kernel in a few months. Rather than wait, I plugged in a supported Ethernet card.

Second, the SATA hard drive driver timed out. Occasionally, the system froze up without many error messages showing up in the system log. I logged in at the console as root and ran “exec tail -f /var/log/messages” (redirecting syslog to a remote machine is a better solution). The next time the system froze up, I saw more output in syslog. It contained approximately the following:

ata1.00 exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x2 frozen
ata1.00 BMDMA stat 0x4 timeout
ata1.00 qc timeout (cmd 0xec)

Google helped me stumble on the following workaround, which seems to work. I don’t know what it does. Edit /etc/grub.conf. Find the lines that say “kernel” and add “acpi=force irqpoll noapic hda=noprobe” to the end, and reboot.

title Fedora Core (2.6.19-1.2911.fc6)
        root (hd0,5)
        kernel /vmlinuz-2.6.19-1.2911.fc6 ro root=LABEL=/ rhgb quiet acpi=force irqpoll noapic hda=noprobe
        initrd /initrd-2.6.19-1.2911.fc6.img

Useful commands (helpfully documented on this blog):

  • dmidecode – tells me what motherboard I have
  • lspci – Tells me what built-in ethernet adapter I have
  • cat /dev/cpuinfo – Tells me about my CPU

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VMWare and Upgrading to Fedora Core 6

I upgraded my desktop machine at work from Fedora Core 5 to Fedora Core 6, and since I run the free VMWare Player (the free VMWare Server is also a fine product), I knew I’d have to get it working after the upgrade. It could have been as simple as running ‘vmware-config.pl’, but it wasn’t.

A known issue with Fedora 6 is that on many single processor systems, the
installer loads an i586 kernel instead of an i686 kernel. The workaround for
this, at install boot-time, is to type “linux i686” — except that it only
works for fresh installs — it doesn’t work for upgrades. An i586 kernel was
installed even though I wanted an i686 kernel, and it created problems when I
went to configure VMWare. vmware-config.pl compiles a kernel module against
kernel headers. I had installed the kernel-devel package to get the kernel
headers. It turns out that I had an i686 kernel-devel package, and it didn’t
mesh up well with the i586 kernel that I didn’t know I had.

Run the following command:
rpm -q --queryformat '%{ARCH} %{NAME}-%{VERSION}-%{RELEASE}\n' kernel kernel-devel

This is how I figured out that I had a mismatch. Here’s what I had:

i586 kernel-2.6.18-1.2869.fc6
i686 kernel-devel-2.6.18-1.2869.fc6

Both of those should read ‘i686’. Here are the commands to run (as the ‘root’ user) to resolve the issue:

  1. yum -y upgrade # to get the latest kernel, etc.
  2. Follow the instructions at http://fedoraproject.org/wiki/Bugs/FC6Common to switch to an i686 kernel.
    • yum -y install yum-utils
    • yumdownloader kernel.i686
    • rpm -ivh --replacefiles --replacepkgs kernel-2*.i686.rpm
  3. reboot
  4. yum -y install kernel-devel
  5. rpm -q --queryformat '%{ARCH} %{NAME}-%{VERSION}-%{RELEASE}\n' kernel kernel-devel # The architecture should be i686
  6. touch /usr/src/kernels/2.6.18-1.2869.fc6-i686/include/linux/config.h
  7. vmware-config.pl

Update

I can’t recommend upgrading to Fedora Core 6 from version 5. My screensaver (gnome-screensaver) wouldn’t unlock — it never even gave me the chance to enter a password. I tried switching to xscreensaver, but it wouldn’t accept my password. After several fruitless google searches for a resolution to either problem, I gave up and decided to install from scratch. Now my screensaver behaves correctly.

When I did a fresh install, it installed the xen kernel. VMware and Xen didn’t play well together for me — I got nearly 100% CPU utilization when I tried to load a guest. I installed the non-xen kernel, booted that kernel, and reconfigured vmware. Now VMware runs great. If I remember correctly, here are the commands I ran as root:

  1. yum -y install kernel
  2. reboot into a non-xen kernel
  3. touch /usr/src/kernels/2.6.18-1.2869.fc6-i686/include/linux/config.h
  4. vmware-config.pl

KVM is the future of virtualization on Linux, from what I gather, so I’m not going to try Xen.

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Article: Crash-only software

Crash-only software: More than meets the eye
by Valerie Henson July 12, 2006:
http://lwn.net/Articles/191059/

Properly implemented, crash-only software produces higher quality, more
reliable code; poorly understood it results in lazy programming. Probably
the most common misconception is the idea that writing crash-only software
is that it allows you to take shortcuts when writing and designing your
code. Wake up, Sleeping Beauty, there ain’t no such thing as a free lunch.
But you can get a more reliable, easier to debug system if you rigorously
apply the principles of crash-only design.

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Advantages of Fedora Core 5 over FC3/FC4

Advantages of Fedora Core 5 over FC3/FC4:

  • Faster boot times
  • Faster Gnome desktop login
  • Faster responsiveness in the Gnome user interface (snappier application menu, etc.)
  • Suspend to disk and suspend to RAM
  • New desktop applications: Beagle desktop search tool, F-spot photo manager, Tomboy note taking application.
  • Firefox: Opening a new window is MUCH faster than with FC4.
  • Most stable installer to date, in my opinion.
  • New HAL integration (hardware abstraction layer) manages USB flash drives, and as a result, they mount on the user’s desktop more quickly than in the past.
  • SELinux targetted policies are much more comprehensive
  • Better wireless NIC support.
  • Xen virtulization.

I find it easier to upgrade rather than reinstall. The upgrade process did not install the new applications that a fresh install would have provided. Therefore, I did a fresh install of FC5 on one machine, and grabbed the package list (FC5 Packages). Then, I upgraded another machine, grabbed the package list ("rpm -qa | sort > upgradepackages.txt“). I generated a ‘diff’ of the two files. Here are the main things I came up with when going from FC4 to FC5:

Missing desktop packages:

  • beagle
  • f-spot
  • frysk
  • tomboy
  • gnome-backgrounds
  • gnome-power-manager
  • gnome-screensaver
  • gnome-user-share
  • nautilus-sendto
  • hal-gnome

Missing non-desktop packages:

  • xorg-x11-fonts-truetype
  • smartmontools
  • systemtap
  • hplip
  • longrun
  • irqbalance
  • glx-utils
  • gmime
  • gmime-sharp
  • dbus-sharp
  • dcraw
  • evolution-sharp

It’s always a good idea to read the release notes:
http://fedora.redhat.com/docs/release-notes/fc5/
Install extra software using yum, or using the graphical application ‘pirut’, or view ‘extra’ packages with your browser:
http://fedoraproject.org/extras/5/i386/repodata/repoview/graphical-internet.group.html
Useful packages (from extras repository):

yum install yum-utils gtweakui themes-backgrounds-gnome nautilus-open-terminal nautilus-image-converter nautilus-actions

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Is open source software sustainable?

Recently, a genuinely concerned coworker expressed concern that “not paying for software [may] ultimately kill the industry” because it encourages people expect something for nothing.

For those who would like this and other common concerns about open software answered, I recommend reading Open Source-onomics. Here’s a list of concerns it addresses:

  • “Open Source is not economically viable”
  • “Not paying for software will ultimately kill the industry”
  • “Why will programmers continue to contribute code if they can’t make money from it?”
  • “Even Open Source development involves effort, so there has to be payment for that effort”
  • “Are Open Source programmers writing themselves out of their jobs?”
  • “But free isn’t natural. There’s no such thing as a free lunch.”
  • “Is software a commodity?”
  • “Who will invest in software development if it doesn’t yield a return?”
  • “Open Source may have a niche, but proprietary commercial products will continue to rule”
  • “Customers will never trust something that is free”
  • “Open Source may release value, but it doesn’t create value”

For those who would like even more detailed reading, I recommend David Wheeler’s “Why Open Source Software? Look at the numbers!“