Monthly Archive for October, 2010

Sentinella waits, executes

Every now and then you come across a handy little application which, when thinking back, could have made your life so much easier at some point in the past.

Sentinella is one of those – a program which will perform a task when something is triggered.

It’s simple, there’s a condition (such as CPU load, memory used, date/time or network traffic) that when met will perform a function that you specify. This might be some hard-coded options like shutdown or reboot, terminate a program or simply sound an alarm, but it can also execute a program. That means that you can really make it do whatever you want!

Once you start a job, Sentinella runs in the background and just pops up once a condition is met, before performing the specified task.

Sentinella

So, you’re uploading something somewhere but need to get to work and can’t wait? No worries, just tell Sentinella that when rsync dies, turn off the machine.

Simple, effective.

It’s packaged for Fedora, so just install and enjoy!

New Fedora website is great

I just noticed that in time for Fedora 14 (which has just gone gold), the project has released a new website.

It’s great. Has lots of useful information about Fedora, especially for new users.

Fedora website

Great work!

Encrypted DVDs and Fedora

The well known RPMFusion repository contains a lot of the useful software which Red Hat doesn’t ship by default (for licensing, patent or legal reasons). It is the amalgamation of several other repositories, including Dribble, Freshrpms, and Livna.

One helpful package that RPMFusion does not package however, is libdvdcss, the free software library which enables Linux to play encrypted DVDs.

Most users keep Livna around for this single purpose, but it is often offline (especially recently). So, here’s another solution – use ATrpms – another third party repository that includes lots of handy software.

The problem is, ATrpms has lots of other software which you might not want to update and which could conflict with the packages from RPMFusion. The solution? Tell yum to only include libdvdcss* packages from that repository. Easy.

To do this, simply add a new repo file (/etc/yum.repos.d/atrpms.repo) for Yum to configure it.
[atrpms]
name=Fedora Core $releasever - $basearch - ATrpms
baseurl=http://dl.atrpms.net/f$releasever-$basearch/atrpms/stable
gpgkey=http://ATrpms.net/RPM-GPG-KEY.atrpms
gpgcheck=1
includepkgs=libdvdcss*

Now, just run the following to update the repo and install libdvdcss (you may wish to remove the old package first, if you have it).
sudo yum check-update
sudo yum install libdvdcss

That’s about it!

-c

Realtek USB Wireless on Linux (Fedora)

When John needed wireless for his computer at home, he bought (probably on my recommendation) a Billion 3011N – a USB wireless N device with the Realtek 8191S(U) chipset. On the box it said that it supported Linux, so I figured it was a pretty safe bet (surely that means there’s a stable driver in the mainline kernel, right?).

Turns out, no. The device has horrible support under Linux and it’s a super pain. The driver disk that came with the box does have a Linux driver, but it doesn’t always compile against the kernel and then there are configuration issues and a custom wpaconfig is required.

Gah.

So John bought another USB wireless dongle.

Anyway, so now I need a USB wireless dongle for my machine and I asked John to buy one of his spare ones from him (he has four or five). He gave me the afore mentioned Billion device. I plugged it into my Fedora 13 box, but it didn’t know much about it. So then I downloaded the open source driver from Realtek, compiled it and loaded the module. The system hard-locked – even Magic Keys couldn’t save it.

I shelved it for a while, until a bloke called Terry Polzin on the Fedora list today posted a request for help with getting a Realtek 8188S(U) working. I replied saying that I had a similar device and shared my experiences.

I told him that there is a driver in staging which supports the device, but unlike Ubuntu, Fedora only ships quality working drivers by default, so no staging drivers are included. It’s easy enough to get them though, just add the RPMFusion Free repository and install their kmod-staging package which (as the name might give away) includes the staging drivers for the current kernel.

Once you have that installed, the r8192s_usb module can be loaded, but the device still needs external (presumably proprietary) firmware to work. Fortunately, although the driver available from Realtek does not include it, it was included on the disk, and is also available in the Billion driver from their website. So, once you have put the firmware in the right place, the device just works.

Here are the steps to get it working (you will need to have RPMFusion enabled, and run these as root).

yum install kmod-staging unzip
depmod -a
wget http://au.billion.com/downloads/3011N/3011N_Linux_Driver.zip
unzip -j 3011N_Linux_Driver.zip "*rtl8192sfw.bin" -d RTL8192SU
mv RTL8192SU /lib/firmware/

Now, plug in your device and check that the module and firmware have been loaded, using dmesg. You should see something like this:

usb 1-2.3: new high speed USB device using ehci_hcd and address 16
usb 1-2.3: New USB device found, idVendor=0bda, idProduct=8172
usb 1-2.3: New USB device strings: Mfr=1, Product=2, SerialNumber=3
usb 1-2.3: SerialNumber: 00e04c000001
==>ep_num:4, in_ep_num:1, out_ep_num:3
==>RtInPipes:3
==>RtOutPipes:4 6 13
==>txqueue_to_outpipemap for BK, BE, VI, VO, HCCA, TXCMD, MGNT, HIGH, BEACON:
1 1 0 0 2 2 2 2 2
Dot11d_Init()
rtl819xU: --->FirmwareDownload92S()

usb 1-2.3: firmware: requesting RTL8192SU/rtl8192sfw.bin
rtl819xU:signature:8192, version:902b, size:30, imemsize:7408, sram size:9688

rtl819xU:--->FirmwareDownloadCode()

rtl819xU:--->FirmwareCheckReady(): LoadStaus(1),
rtl819xU:<---FirmwareCheckReady(): LoadFWStatus(1), rtStatus(0)

rtl819xU:--->FirmwareDownloadCode()

rtl819xU:--->FirmwareCheckReady(): LoadStaus(2),
rtl819xU:-->FirmwareEnableCPU()

rtl819xU:IMEM Ready after CPU has refilled.

rtl819xU:<--FirmwareEnableCPU(): rtStatus(0x0)

rtl819xU:<---FirmwareCheckReady(): LoadFWStatus(2), rtStatus(0)

rtl819xU:--->FirmwareDownloadCode()

rtl819xU:--->FirmwareCheckReady(): LoadStaus(3),
rtl819xU:DMEM code download success, CPUStatus(0x3f)

rtl819xU:Polling Load Firmware ready, CPUStatus(ff)

rtl819xU:FirmwareCheckReady(): Current RCR settings(0x157e20e)

rtl819xU:<---FirmwareCheckReady(): LoadFWStatus(3), rtStatus(0)

rtl819xU:Firmware Download Success!!

ADDRCONF(NETDEV_UP): wlan0: link is not ready
=====>rtl8192SU_link_change 1
<=====rtl8192SU_link_change 2

Now, you should have a wireless device and network interface, which you can check with iwconfig and ifconfig -a.

wlan0 802.11b/g/n Mode:Managed Frequency=2.422 GHz
Access Point: Not-Associated Bit Rate:130 Mb/s
Retry min limit:7 RTS thr:off Fragment thr:off
Power Management:off
Link Quality=0/100 Signal level=0 dBm Noise level=0 dBm
Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
Tx excessive retries:0 Invalid misc:0 Missed beacon:0

And that's it. The device should now work with NetworkManager, etc.

The main downside here (apart from the obvious) is that you will be relying on RPMFusion to build an updated kmod-staging version when you get a Fedora kernel update. Sometimes this might not happen before you get your kernel, so when you reboot, you lose your wireless (because there's no driver). If so, boot to your older kernel for a while, or build the driver yourself, or create an akmod instead of kmod.

Ubuntu users should be able to just put the firmware in the right place, as their kernel ships with the unstable drivers by default.

-c