New Debian release, Wi-Fi tutorial from Omer

A couple of quick news items on Sunday morning:

Some of you may have noticed that we posted a new Debian “squeeze” release on the downloads page yesterday. This contains several performance enhancements, including enabling the 128K system L2 cache for the first time, and Dom’s first-cut ALSA drivers.

Omer Kilic has produced a tutorial showing how to get some brands of Wi-Fi module to work with the latest Debian image.


mark avatar

sound cannot wait for my pi

Florin Moloz avatar

Is the cache really necessary?
The processor is 700 MHz fast and the RAM should be close enough.

asb avatar

There is a noticeable performance boost.

Alex Langer avatar

Just because the RAM is piggybacked doesn’t mean it’s close or fast enough. It’s a matter of RAM clock speed, which isn’t automatically the same as of the CPU core and also a matter of the bus width.

You’d usually expect a significant performance boost in real time scenarios using a 2nd level cache on a 700 MHz CPU. Remember, we’ve been having mass usage of 2nd Level caches since the days of the Intel 80386.

However, Eben noted in a another thread of this forum, that Broadcom tends to keep the 2nd level cache turned off as it is considered being a bit far away from the core. There’s situations where the cache improves performacne, there’s situations where it decreases it.

May have to do with the actual implementation, bus clocks, bus widths, waitstates.. Maybe within the livetime of the chip the RAM chip speed has been increased and the cache speed has not. Maybe we’ll never know…

Gert avatar

The L2 cache is there for the GPU too. So if you enable the L2 for the ARM your GPU will slow down. If your application is mostly ARM your performance goes up. If you play back 1080p30 videos your performance is likely to go down

oninoshiko avatar

Is it possible to make it use it ONLY for the CPU (not the GPU?)
Is it write through or write back?
I’m not sure I understand why it speeds up the CPU but slows down the GPU, could you elaborate on that?
Thanks, Gert!

Gert avatar

Each cacheline used by the ARM is taken away from the GPU and vice versa. I’m short on space here so I suggest look up how a cache works.

Semtex avatar

I notice Debian is now the recommended build. Element14 has even removed Fedora 14 Remix from its download page. Has there been any feedback from the Seneca folks when we might get a quality Fedora release for the RasPi?

Andy Cater avatar

Not in contact with those at Seneca but – having built the Fedora 14 for themselves, they were looking to rebase on Fedora 17, probably in the winter term. Fedora are still undecided on whether to build ARM as a primary architecture – the latest Fedora release has just been delayed, as is traditional :(
Don’t hold your breath in waiting

Lobster avatar

Does Squeeze require a 4Gig SD card? I am off to Argos in a moment to check out their transcend SD cards, which have been recommended. Then I gotta cut that Squeeze down to Puppy Linux size – for our pre alpha . . . well that is the plan . . .Downloading the Squeeze . . .

asb avatar

Nope, it’s a 2 gig image.

Alex Buell avatar

Is this method of enabling the L2 cache documented anywhere? For those of us who might want to roll our own operating system…

JamesH avatar

I think its done in the blob, so will be on by default once you are using the most up to date version.

Gordon avatar

The L2 cache can be enabled / disabled from the config.txt file stored on the SD card…

JamesH avatar

Ah, thanks Gordon.

debianist avatar

debian rocks, as usual :)

FrozenFirestorm avatar

Awesome :D

kf6snj avatar

Guess I will just have to download the new Debian image and then rewrite my SDcard for the PI. Still waiting for my turn to order. Working on the associated hardware and software for it now.

Mike Thompson avatar

Great stuff. I’m very happy the Foundation is moving the Debian release along. I’m making good progress on a Raspberry Pi friendly flavor of Debian armhf and the improvements made on the Debian armel side should move right on over to the hard float version. I hope to have an initial set of Debian armhf hard float packages available publicly within a week or two that RPi users can play around with. There is a LOT of package building still to do, but the initial set of packages will provide a minimal install of Debian armhf along with all the development tools to build other software/packages or run benchmark tests. For anyone interested in a hard float version of Debian wheezy, keep an eye out in the forums for news.

Gert avatar

What happened to the forum? If I use my forum link it says: phpBB
“Sorry but this board is currently unavailable.”

ukscone avatar

Eben is moving us to the land of unicorns and rainbows of phpBB and away from the Mordor of Simple:Press

Dandapani avatar

Too bad. Not a fan of Debian. Been RH and now Fedora user for too many years.

cnxsoft avatar

Is there a more detailed ChangeLog? Just out of curiosity.

Edy Aldea avatar

How about a cover?
To protect Rapsberry Pi.

JamesH avatar

Search the forums for ‘cases’ and prepare to be amazed.

Alex avatar

Great video, cant wait untill i get mine

are you able to perform terminal services through the device and create a VPN

Gregor avatar

It seems to me that there should be at least 1 more USB port on it. Now you have USB keyboard and USB mouse (which are essential for GUI work) and then there is nothing left for any other peripherals (such as USBwi-fi, USBprinter, USBanything else…)

Ajmay avatar

Buy a USB hub. The Raspi is an ultra low cost unit. More USB ports equals more cost.

Jmarcelino avatar

Unfortunately the driver for my Realtek 8191S USB adapter (rtl8192su_usb) is still not available on the ARM :(

ps: posted from my Raspberry Pi (but X11 is ver very slow, took me 5 minutes just to write this!)

Lars T. Hansen avatar

This blog post[1] wrote about a firmware blob that need exists in a specific directory.
The firmware blob is pushed to the Realtek 8191US chip. If doesn’t have that blob is does nothing.

If you are lucky: the driver is included in a new version of the kernel


jmarcelino avatar

Unfortunately the Wifi driver I need (rtl8192su_usb) is still in Debian kernel staging and not available on the Pi distribution :(

ps : Tried posting this on the Pi that just arrived, but X11 is insanely slow to use :( Took me over 5 minutes to just write this! By then the password had already changed.

Has anyone managed to post something here from their Raspberry Pi’s?

jmarcelino avatar

I see posting here actually worked (even after getting a WordPress error) yay!

JamesH avatar

Have you got the very very latest Debian image? release within last couple of days. Has much better wireless USB support. That driver definitely works as I tried it, but that was with a custom kernel build with the staging drivers turned on.

jmarcelino avatar

Yes, very latest downloaded today. It doesn’t have that driver :(

Did you compile the kernel with staging drivers on the Pi or was it cross-compiled? I don’t have a setup to crosscompile yet.


JamesH avatar

This was cross compiled on a Broadcom build machine, so I cannot tell you specifically how to set it up I’m afraid.

pdp7 avatar

Do you know if those additional net/wireless compiled kernel modules (like r8712u) are available somewhere for this new version of Debian?

Also, I think you were the person that added the RTL8187-based Netgear adapter to the eLinux wiki, right? I tried two RTL8187-based adapters I have but no luck so far even with latest Debian (it does load the driver but iwlist produces no results). Do you recall any additional details from when you tested (if it was you ;)?

Drew Fustini

JamesH avatar

Yes, I did some testing there. I’ll check with the guy working on wireless here, but I think he found that the firmware had changed – so he needed to download a different firmware (8KB vs 4KB?) rather than use apt-get…. I’ll try and find out.

pdp7 avatar

Thanks, JamesH!

davej avatar

Is the article at still applicable as to the kernel version or do we have to compile a new one from scratch?

PS: In view of the fact that it is going to be a while before most of us get our slice, maybe an up to date version of this article (or a link to it) belongs in the quick start guide ?

cnxsoft avatar

I haven’t tried but it should work.

There is also a simpler way where you don’t need to do the dd part, you can use:

qemu-system-arm -M versatilepb -cpu arm1176 -m 192 -hda debian6-13-04-2012.img -kernel zImage_3.1.9 -append “root=/dev/sda2” -redir tcp:2222::22

Dave Joubert avatar

I have booted the system with the previous kernel and the current (debian6-13-04-2012.img) image after unpacking it to an .ext4. Trying to do it directly from the image (as per the above) failed for me (but might just have been finger trouble). Did not try to go beyond just the login stage.

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