Steam on EL6 (RHEL6 / Scientific Linux 6 / CentOS 6)

The fact that Steam have decided to only officially support .deb based distributions, and only relatively recent ones at that has been a pet peeve of mine for quite some time. While there are ways around the .deb only official package availability (e.g. alien), the library requirements are somewhat more difficult to reconcile. I have finally managed to get Steam working on EL6 and I figure I’m probably not the only one interested in this, so I thought I’d document it.

Different packages required to do this have been sourced from different locations (e.g. glibc from fuduntu project, steam src.rpm from (not really a source rpm, it just packages the steam binary in a rpm), most of the rest from more recent Fedoras, etc.). I have rebuilt them all and made them available in one place.

You won’t need all of them, but you will need at least the following:


First install some the dependencies from the standard distribution packages:

yum install gtk2-engines.i686 \
            openal-soft.i686 \
            alsa-plugins-pulseaudio.i686 \

The install the updated packages:

rpm -Uvh glibc-2.15-60.el6.i686.rpm \
         glibc-2.15-60.el6.x86_64.rpm \
         glibc-common-2.15-60.el6.x86_64.rpm \
         glibc-devel-2.15-60.el6.x86_64.rpm \
         glibc-headers-2.15-60.el6.x86_64.rpm \
         libtxc_dxtn-1.0.0-2.1.i686.rpm \
         SDL2-2.0.3-2.el6.i686.rpm \
         steam- \
         xz-5.0.5-1.el6.x86_64.rpm \
         xz-compat-libs-5.0.5-1.el6.x86_64.rpm \
         xz-libs-5.0.5-1.el6.x86_64.rpm \

If you have pyliblzma from EPEL installed (required by, e.g. mock), updated xz-lzma-compat package will trigger a python bug that causes a segfault. This will incapacitate some python programs (yum being an important one). If you encounter this issue and you must have pyliblzma for other dependencies, reinstall the original xz package versions after you run steam for the first time. Updated xz only seems to be required when the steam executable downloads updates for itself.

Finally, run steam, log in, and let it update itself.

One of the popular games that is available on Linux is Left 4 Dead 2. I found that on ATI and Nvidia cards it doesn’t work properly in full screen mode (blank screen, impossible to Alt-Tab out), but it does work on Intel GPUs. It works on all GPU types in windowed mode. Unfortunately, it runs in full screen mode by default, so if you run it without adjusting its startup parameters you may have to ssh into the machine and forcefully kill the hl2_linux process. To work around the problem, right click on the game in your library, and go to properties:

Click on the “SET LAUNCH OPTIONS…” button:

You will probably want to specify the default resolution as well as the windowed mode to ensure the game comes up in a sensible mode when you launch it.
Add “-windowed -w 1280 -h 720” to the options, which will tell L4D2 to start in windowed mode with 1280×720 resolution. The resolution you select should be lower than your monitor’s resolution.

If you did all that, you should be able to hit the play button and be greeted with something resembling this:

ATI cards using the open source Radeon driver (at least with the version 7.1.0 that ships with EL6) seem to exhibit some rendering corruption, specifically some textures are intermittently invisible. This leads to invisible party members, enemies, and doors, and while it is entertaining for the first few seconds it renders the game completely unplayable. I have not tested the ATI binary driver (ATI themselves recommend the open source driver on Linux for older cards and I am using a HD6450).

Nvidia cards work fine with the closed source binary driver in windowed mode, and performance with a GT630 constantly saturates 1080p resolutions with everything turned up to maximum. I have not tested with the nouveau open source driver.

With Intel GPUs using the open source driver, everything works correctly in both windowed and full screen mode, but the performance is nowhere nearly as good as with the Nvidia card. With all the settings set to maximum, the performance with the Intel HD 4000 graphics (Chromebook Pixel) is roughly the same at 1920×1200 resolution as with the Radeon HD6450, producing approximately 30fps. The only problem with playing it on the Chromebook Pixel is that the whole laptop gets too hot to touch, even with the fan going at full speed. Not only does the aluminium casing get too hot to touch, the plastic keys on the keyboard themselves get painfully hot. But that story is for another article.

QNAP TS-421 – Review, Modification and RedSleeve Linux


With the RedSleeve Linux release rapidly approaching, I needed a new server. The current one is a DreamPlug with an SSD and although it has so far worked valiantly with perfect reliability, it doesn’t have enough space to contain all of the newly build RPM packages (over 10,000 of them, including multiple versions the upstream distribution contains), and is a little lower on CPU (1.2GHz single core) and RAM (512MB) than ideal to handle the load spike that will inevitably happen once the new release becomes available. I also wanted a self contained system that doesn’t require special handling with many cables hanging off of it (like SATA or USB external disks). I briefly considered the Tonido2 Plug, but between the slower CPU (800MHz) and the US plug, it seemed like a step backward just for the added tidyness of having an internal disk.


The requirements I had in mind needed to cover at least the following:
3) At least a 1.2GHz CPU
4) At least 512MB of RAM
5) Everything should be self contained (no externally attached components)


Very quickly the choice started to focus on various NAS appliances, but most of them had relatively non-existant community support for running custom Linux based firmware. The one exception to this is QNAP NAS devices which have rather good support from the Debian community; and where there is a procedure to get one Linux distribution to run, getting another to run is usually very straightforward. After a quick look through the specifications, I settled on the QNAP TS-421, which seems to be the highest spec ARM based model:

CPU: 2GHz ARMv5 Marvell Kirkwood (same as in the DreamPlug but 66% higher clock speed)
RAM: 1GB (twice as much as DreamPlug)
SATA: 4x 3.5″ SATA disk trays, based on the excellent Marvell 88SX7042 PCIe SATA controller
eSATA: 2x
Ethernet: 2x Gigabit (same as DreamPlug)
USB: 2x 2.0, 2x 3.0


At the time when I ordered the QNAP TS-421, it was listed as supporting 4TB drives – the largest air filled that were available at the time. I ordered 4x 4TB HGST drives because they are known to be more reliable than other brands. In the 10 days since then Toshiba announced 5TB drives, but these are not yet commercially available. I briefly considered the 6TB Helium filled Hitachi drives, but these are based on a new technology that has not been around for long enough for long term reliability trends to emerge – and besides, they were prohibitively expensive (£87/TB vs £29/TB for the 4TB model), and to top it all off, they are not available to buy.


Once the machine arrived, it was immediately obvious that the build quality is superb. One thing, however, bothered me immediately – it uses an external power brick, which seems like a hugely inconvenient oversight on an otherwise extremely well designed machine.

In order to make playing with alternative Linux installations I needed to get serial console access. To do this you will need a 3.3V TTL serial cable, same as what is used on the Raspberry Pi. These are cheaply available from many sources. One thing I discovered the hard way after some trial and error is that you need to invert the RX and TX lines between the cable and the QNAP motherboard, i.e. RX on the cable needs to connect to TX on the motherboard, and vice versa. There is also no need to connect the VCC line (red) – leave it disconnected. My final goal was to get RedSleeve Linux running on this machine, the process for which is documented on the RedSleeve wiki so I will not go into it here.


One thing that becomes very obvious upon opening the QNAP TS-421 is that there is ample space inside it for a PSU, which made the design decision to use an external power brick all the more ill considered. So much so that I felt I had to do something about it. It turns out the standard power brick it ships with fits just fine inside the case. Here is what it looks like fitted.

It is very securely attached using double sided foam tape. Make sure you make some kind of a gasket to fit between the PSU and the back of the case – this is in order to prevent upsetting the crefully designed airflow through the case. I used some 3mm thick expanded polyurethane which works very well for this purpose. The cable tie is there just for extra security and to tidy up the coiled up DC cable that goes back out of the case and into the motherboard’s power input port. This necessitated punching two 1 inch holes in the back of the case – one for the input power cable and one for the 12V DC output cable. I used a Q.Max 1 inch sheet metal hole punch to do this. There is an iris type grommet for the DC cable to prevent any potential damage arising from it rubbing on the metal casing.

The finished modification looks reasonably tidy and is a vast improvement on a trailing power brick.

One other thing worth mentioning is that internalizing the PSU makes no measurable difference to internal temperatures with the case closed. In fact, if anything the PSU itself runs cooler than it does on the outside due to the cooling fan inside the case. The airflow inside the case is incredibly well designed, hence the reason why it is vital you use a gasket to seal the gap between the power input port on the PSU and the back of the case. To give you the idea of just how well the airflow is designed, with the case off, the HGST drives run at about 50-55C idle and 60-65C under load. With the case on they run at about 30C idle and 35C under full load (e.g. ZFS scrub or SMART self tests).

Virtualized Gaming: Nvidia Cards, Part 3: How to Modify 2xx – 4xx series GeForce into a Quadro

here has been a large amount of interest in the previous two articles in this series and many calls for a modifying guide. In this article I will explain the details of how to modify your Fermi based GeForce card into a corresponding equivalent Quadro card. Specifically, you the following:

GeForce GTS450GF106Quadro 2000
GeForce GTX470GF100Quadro 5000
GeForce GTX480GF100Quadro 6000

The Tesla (2xx/3xx) and Fermi (4xx) series of GPUs can be modified by modifying the BIOS. Earlier cards can also be modified, but the modification is slightly different to what is described in this article. There is no hardware modification required on any of these cards. The modification is performed by modifying what is known as the “straps” that configure the GPU at initialization time. The nouveau project (free open source nvidia driver implementation for Xorg) has reverse engineered and documented some of the straps, including the device ID locations. We can use this to change the device ID the card reports. This causes the driver to enable a different set of features that it wouldn’t normally expose on a gaming grade card, even though the hardware is perfectly capable of it (you are only supposed to have those features if you paid 4-8x more for what is essentially the same (and sometimes even inferior) card by buying a Quadro).

The main benefit of doing this modification is enabling the card to work in a virtual machine (e.g. Xen). If the driver recognizes a GeForce card, it will refuse to initialize the card from a guest domain. Change the card’s device ID into a corresponding Quadro, and it will work just fine. On the GF100 models, it will even enable the bidirectional asynchronous DMA engine which it wouldn’t normally expose on a GeForce card even though it is there (on GF100 based GeForce cards only a unidirectional DMA engine is exposed). This can potentially significantly improve the bandwidth between the main memory and GPU memory (although you probably won’t notice any difference in gaming – it has been proven time and again that the bandwidth between the host machine and the GPU is not a bottleneck for gaming workloads).

Another thing that this modification will enable is TCC mode. This is particularly of interest to users of Windows Vista and later because it avoids some of the graphics driver overheads by putting the card in a mode only used for number-crunching. Note: Although most Quadros have TCC mode available, you may want to look into modifying the card into a corresponding Tesla model if you are planning to use it purely for number crunching. You can use the same method described below, just find a Tesla based on the same GPU with equal or lower number of enabled shader processors, find it’s device ID in the list linked at the bottom of the article, and change the device IDs using the strap.

Before you begin even contemplating this make sure you know what you are doing, and that the instructions here come with no warranty. If you are not confident you know what you are doing, buy a pre-modified card from someone instead or get somebody who does know what they are doing to do it for you.

To do this, you will require the following:

  • NVFlash for Windows and/or NVFlash for DOS
    Note: You may need to use the DOS version – for some reason the Windows version didn’t work on some of my Fermi cards. If you use the DOS version, make sure you have a USB stick or other media set up to boot into DOS.
  • Hex editor. There are many available. I prefer to use various Linux utilities, but if you want to use Windows, HxD is a pretty good hex editor for that OS. It is free, but please consider making a small donation to the author if you use it regularly.
  • Spare Graphics card, in case you get it wrong. If you are new to this, your boot graphics card (the spare one, not the one you are planning to modify) should preferably not be an Nvidia one (to avoid potential embarrassment of flashing the wrong card). Skip this part at your peril.

On Fermi BIOS-es the strap area is 16 bytes long and it starts at file offset 0x58. Here is an example based on my PNY GTX480 card:
0000050: e972 2a00 de10 5f07 ff3f fc7f 0040 0000 .r*..._..?...@..
0000060: ffff f17f 0000 0280 7338 a5c7 e92d 44e9 ........s8...-D.

The very important thing to note here is that the byte order is little-endian. That means that in order to decode this easily, you should re-write the highlighted data as:
7FFC 3FFF 0000 4000 7FF1 FFFF 8002 0000

This represents two sets of straps, each containing an AND mask and an OR mask. The hardware level straps are AND-ed with the AND mask, and then OR-ed with the OR mask.

The bits that control the device ID are 10-13 (ID bits 0-3) and 28 (bit 4). We can ignore the last 8 bytes of the strap since all the bits controlling the device ID is in the first 8 bytes.

This makes the layout of the strap bits we need to change a little more obvious:

Fxx4xxxx xxxxxxxx xx3210xx xxxxxxxx
   ^                ^^^^
   |                ||||-pci dev id[0]
   |                |||--pci dev id[1]
   |                ||---pci dev id[2]
   |                |----pci dev id[3]
   |---------------------pci dev id[4]
F - cannot be set, always fixed to 0

The device ID of the GTX480 is 0x06C0. In binary, that is:
0000 0110 1100 0000
We want to modify it into a Quadro 6000, which has the device ID 0x06D8. In binary that is:
0000 0110 1101 1000

The device ID differs only in the low 5 bits, which is good because we only have the low 5 bits available in the soft strap.

So we need to modify as follows
From:   0000 0110 1100 0000
To:     0000 0110 1101 1000
Change: xxxx xxxx xxx1 1xxx

We only need to change two of the strap bits from 0 to 1. We can do this by only adjusting the OR part of the strap.

It is easier to see what is going on if we represent this as follows:

ID Bit:   4                  32 10
Strap: -xxA xxxx xxxx xxxx xxAx xxxx xxxx xxxx
Old Strap:
AND-0: 7F        FC        3F        FF
       0111 1111 1111 1100 0011 1111 1111 1111
OR-0:  00        00        40        00
       0000 0000 0000 0000 0100 0000 0000 0000
New Strap:
AND-0: 7F        FC        3F        FF
       0111 1111 1111 1100 0011 1111 1111 1111
OR-0:  10        00        60        00
       0001 0000 0000 0000 0110 0000 0000 0000

Note that in the edit mask above, bit 31 is marked as “-“. Bit 31 is always 0 in both AND and OR strap masks.
Bits we must keep the same are marked with “x”. Bits we need to amend are marked with “A”.

So what we need to do is flash the edited strap to the card. We could do this directly in the BIOS, but this would require calculating the strap checksum, which is tedious. Instead we can use nvflash to take care of the strap rewrite for us, and it will take care of the checksum transparently.
The new strap is:
0x7FFC3FFF 0x10006000 0x7FF1FFFF 0x80020000
The second pair is unchanged from where we read from the BIOS above. Make sure you have ONLY changed the device ID bits and that your binary to hex conversion is correct – otherwise you stand a very good chance of bricking the card.

We flash this onto the card using:
nvflash --index=X --straps 0x7FFC3FFF 0x10006000 0x7FF1FFFF 0x00020000
1) The last OR strap is 0x00020000 even though the data in the BIOS reads as if it should be 0x80020000. You cannot set the high bit (the left-most one) to 1 in the OR strap (just like you cannot set it to 0 in the AND strap). Upon flashing nfvlash will turn the high bit to 1 for you and what will end up in the BIOS will be 0x80020000 even though you set it to 0x00020000. This is rather unintuitive and poorly documented.
2) You will need to check what the index of the card you plan to flash is using nvflash -a, and replace X with the appropriate value.

Here is an example (from my GTX480, directly corresponding the the pre-modification fragment above) of how the ROM differs after changing the strap:

0000050: e972 2a00 de10 5f07 ff3f fc7f 0060 0010 .r*..._..?...`..
0000060: ffff f17f 0000 0280 7338 a597 e92d 44e9 ........s8...-D.

The difference at byte 0x6C is the strap checksum that nvflash calculated for us.

Reboot and your card should now get detected as a Quadro 6000, and you should be able to pass it through to your virtual machine without problems. I have used this extensively to enable me to pass my GeForce 4xx series cards to my Xen VMs for gaming. I will cover the details of virtualization use with Xen in a separate article. Note that I have had reports of cards modified using this method also working virtualized using VMware vDGA, so if this is your preferred hypervisor, you are in luck. Quadro 5000 and 6000 are also listed as supported for VMware vSGA virtualization, so that should work, too – if you have tried vSGA with a modified GeForce card, please post a comment with the details.

The same modification method described here should work for modifying any Fermi card into the equivalent Quadro card. Simply follow the same process. You may find this list of Nvidia GPU device IDs useful to establish what device ID you want to modify the card to. The GPU should match between the GeForce card the the Quadro/Tesla/Grid you are modifying to – so check which Nvidia card uses which GPU.

Many thanks to the nouveau project for reverse engineering and documenting the initialization straps, and all the people who have contributed to the effort.

In the next article I will cover modifying Kepler GPU based cards. They are quite different and require a different approach. There are also a number of pitfalls that can leave you chasing your tail for days trying to figure out why everything checks out but the modification doesn’t work (i.e. the card doesn’t function in a VM).

IBM T221 3840×2400 204dpi Monitor – Part 7: Positive Update

For once it would appear that I have a positive update on the subject of Nvidia drivers. It would seem that patching the latest (319.23) driver is no longer required on Linux. Even better, there is a way to achieve a working T221 setup without RandR getting in the way by insisting the two halves are separate monitors. I covered the issues with Nvidia drivers in a previous article.

The build part now works as expected out of the box. Simply:

bash ./

and everything should “just work”.

Best of all, there appears to be a workaround for the RandR information being visible even when Xinerama is being overridden. It turns out, Ximerama and RandR seem to be mutually exclusive. So even though the option disabling RandR explicitly seems to get silently ignored, enabling Xinerama fixes that problem. And since the Nvidia driver’s Xinerama info override still works, this solves the problem!

You may recall from a previous article the following in xorg.conf:

Section "ServerLayout"
	Identifier "Layout0"
	Screen 0 "Screen0" 0 0
	Option "Xinerama" "0"
Section "Screen"
	Identifier "Screen0"
	Option "NoTwinViewXineramaInfo" "True"
	Option "TwinView" "1"
	Option "TwinViewOrientation" "RightOf"
	Option "metamodes" "DFP-0:1920x2400, DFP-3:1920x2400"

It turns out the solution is to simply enable Xinerama:

Section "ServerLayout"
	Identifier "Layout0"
	Screen 0 "Screen0" 0 0
	Option "Xinerama" "1"

This implicitly disables RandR and Nvidia driver’s Xinerama info override takes care of the rest. Magic. 

If you are still having problems when using KDE, there is another trick you can use to force xinerama and disable RandR. Ammend the following line in kdmrc:

ServerArgsLocal=-extension RANDR +xinerama -nr -nolisten tcp

WQUXGA – IBM T221 3840×2400 204dpi Monitor – Part 6: Regressing Drivers and Xen

I recently built a new machine, primarily because I got fed up of having to stop what I’m working on and reboot from Linux into Windows whenever my friends and/or family invited me to join them in a Borderlands 2 session. Unfortunately, my old machine was just a tiny bit too old (Intel X38 based) to have full, bug-free VT-d/IOMMU support required for VGA passthrough to work, so after 5 years, I finally decided it was time to rectify this. More on this in another article, but the important point I am getting to is that VGA passthrough requires a recent version of Xen. And there this part of the story really begins.

Some of you may have figured out that RHEL derivatives are my Linux distribution of choice (RedSleeve was a big hint). Unfortunately, RedHat have dropped support for Xen Dom0 kernels in EL6, but thankfully, other people have picked up the torch and provide a set of up to date, supported Xen Dom0 kernels and packages for EL6. So far so good. But it was never going to be so simple, at a time when drivers are getting increasingly dumber, feature sparse and more bloated at the same time. That is really what this story is about.

For a start, a few details about the system setup that I am using, and have been using for years.

  • I am a KDE, rather than Gnome user. EL6 comes with KDE 4, which use X RandR rather than Xinerama extensions to establish the geometry of the screen layout. This isn’t a problem in itself, but there is no way to override whatever RandR reports, so on a T221 you end up with a regular desktop on half of the T221, and an empty desktop on the other, which looks messy and unnatural.
  • This is nothing new – I have covered the issue before in part 1 (ATI, fakexinerama) and part 3 (nvidia, twinview) of this series of articles. There are, however, further complications now:
  1. EL6 had had a Xorg package update that bumped the ABI version to from 10 to 11
  2. Nvidia drivers have changed the way TwinView works after version 295.x (TwinView option in xorg.conf is no longer recognized)
  3. Nvidia drivers 295.x do not support Xorg ABI v11.
  4. Nvidia kernel drivers 295.x do not build against kernels 3.8.x.

And therein lies the complication.

Nvidia drivers v295 when used with options TwinView and NoTwinViewXineramaInfo also seem to override RandR geometry to the show there is a single, large screen available, rather than two screens. This is exactly what we want when using the T221. Drivers after 295.x (304.x seems to be the next version), don’t recognize the TwinView configuration option, and while they provide Xinerama geometry override when using the NoTwinViewXineramaInfo option, they do not override RandR information any more. This means that you end up with a desktop that looks as you would expect it to if you used two separate monitors (e.g. status bar is only on the first screen, no wallpaper stretch, etc.), rather than a single, seamless desktop.

As you can see, there is a large compound issue in play here. We cannot use the 295.x drivers, because

  1. They don’t support Xorg ABI 11 – this can be solved by downgrading the xorg-x11-server-* and xorg-x11-drv-* packages to an older version (1.10 from EL 6.3). Easily enough done – just make sure you add xorg-x11-* to your exclude line in /etc/yum.conf after downgrading to avoid accidentally updating them in the future.
  2. They don’t build against 3.8.x kernels (which is what the Xen kernel I am using is – this is regardless of the long standing semi-allergy of Nvidia binary drivers to Xen). This is more of an issue – but with a bit of manual source editing I was able to solve it.

Here is how to get the latest 295.x driver (295.75) to build against Xen kernel 3.8.6. You may need to do this as root.

Kernel source acquisition and preparation:

rpm -ivh kernel-xen-3.8.6-1.el6xen.src.rpm
cd ~/rpmbuild/SPEC
rpmbuild -bp kernel-xen.spec
cd ~/rpmbuild/BUILD/linux-3.8.6
cp /boot/config-3.8.6-1.el6xen.x86_64 .config
make prepare
make all

Now that you have the kernel sources ready, get the Nvidia driver 295.75, the patch, patch it and build it.

bash ./ --extract-only
patch < NVIDIA-Linux-x86_64-295.75.patch
cd NVIDIA-Linux-x86_64-295.75
export SYSSRC=~/rpmbuild/BUILD/linux-3.8.6
cp /usr/include/linux/version.h $SYSSRC/include/linux/
./nvidia-installer -s

And there you have it Nvidia driver 295.75 that builds cleanly and works against 3.8.6 kernels. The same xorg.conf given in part 3 of this series will continue to work.

It is really quite disappointing that all this is necessary. What is more concerning is that the ability to use a monitor like the T221 is diminishing by the day. Without the ability to override what RandR returns, it may well be gone completely soon. It seems the only remaining option is to write a fakerandr library (similar to fakexinerama). Any volunteers?

It seems that Nvidia drivers are both losing features and becoming more bloated at the same time. 295.75 is 56MB. 304.88 is 65MB. That is 16% bloat for a driver that is regressively missing a feature, in this case an important one. Can there really be any doubt that the quality of software is deteriorating at an alarming rate?

Clevo M860TU / Sager NP8662 / mySN XMG5 GPU (GTX260M / FX 3700M) Replacement / Upgrade and Temperature Management Modifications

Recently, my wife’s Clevo M860TU laptop suffered a GPU failure. Over our last few Borderlands 2 sessions, it would randomly crash more and more frequently, until any sort of activity requiring 3D acceleration refused to work for more than a few seconds. The temperatures as measured by GPU-Z looked fine (all our computers get their heatsinks and fans cleaned regularly), so it looked very much like the GPU itself was starting to fail. A few days later, it failed completely, with the screen staying permanently blank.

The original GPU in it was an Nvidia GTX260M. These proved near impossible to come by in MXM III-HE form factor. Every once in a while a suitable GTX280M would turn up on eBay, but the prices were quite ludicrous (and consequently they would never sell, either). Interestingly, Nvidia Quadro FX 3700M MXM III-HE modules seem to be fairly abundant and reasonably priced. This is interesting considering that they cost several times more than the GTX280M new. Their spec (128 shaders, 75W TDP) is identical.

MXM-III HE Nvidia Quadro FX 3700M

The GTX260M has 112 shaders and a lower TDP of 65W, so the cooling was going to be put under increased strain (especially since I decided to upgrade it from a dual core to a quad core CPU at the same time – more on that later). Having fitted it all (it is a straight drop-in replacement, but make sure you use shims and fresh thermal pads for the RAM if required to ensure proper thermal contact with the heatsink plate), I ran some stress tests.

Within 10 minutes of OCCT GPU test, it hit 97C, and started throttling and producing errors. I don’t remember what temperatures the GTX260M was reaching before, but I am quite certain it was not this high. I had to find a way to reduce the heat production of the GPU. Given the cooling constraints in a laptop, even a well designed one like the Clevo M860TU, the only way to reduce the heat was by reducing either the clock speed or the voltage – or both. Since the heat produced by a circuit is proportional to the multiple of the clock speed and the square of the voltage, reducing the voltage has a much bigger effect than reducing the clock speeds. Of course, reducing the voltage necessitates a reduction in clock speed to maintain stability. The only way to do this on an Nvidia GPU is by modifying the BIOS. Thankfully, the tools for doing so are readily available:

After some experimentation, it wasn’t difficult to find the optimal setting given the cooling constraints. The original settings were:

  • Core: 550MHz
  • Shaders:1375MHz
  • Memory: 799MHz (1598MHz DDR)
  • Voltage: 1.03V (Extra)
  • Temperature: Throttles  at 97C and gets unstable (OCCT GPU test)
  • FPS: ~17

The settings I found that provided 100% stability and reduced the temperatures down to a reasonable level are as follows:

  • Core: 475MHz
  • Shaders: 1250MHz
  • Memory: 799MHz (1598MHz DDR)
  • Voltage: 0.95V (Extra)
  • Temperature: 82C peak (OCCT GPU test)
  • FPS: ~16

The temperature drop is very significant, but the performance reduction is relatively minimal. It is worth noting that OCCT is specifically designed to produce maximum heat load. Playing Borderlands 2 and Crysis with all the settings set to maximum at 1920×1200 resulted in peak temperatures around 10C lower than the OCCT test.

While I had the laptop open I figured this would be a good time to upgrade the CPU as well. Not that I think that the 2.67Hz P9600 Core2 was underpowered, but with the 2.26GHz Q9100 quad core Core2s being quite cheap these days, it seemed like a good idea. And considering that when overclocking the M860TU from 1066 to 1333FSB I had to reduce the multiplier on the P9600 (not that there was often any need for this), the Q9100’s lower multiplier seemed like a promising overall upgrade. The downside, of course, was that the Q9100 is rated to a TDP of 45W compared to P9600’s 25W. Given the heatsink on the Clevo M860TU is shared between the CPU and the GPU, this no doubt didn’t help the temperatures observed under OCCT stress testing. Something could be done about this, too, though.

Enter RMClock – a fantastic utility for tweaking VIDs to achieve undervolting on x86 CPUs at above minimum clock speed. Intel Enhanced SpeedStep reduces both the clock speed and the voltage when applying power management. The voltage VID and clock multipliers are overrideable (within the minimum and maximum for both hard-set in the CPU), which means that in theory, with a very good CPU, we could run the maximum multiplier and minimum VID to reduce power saving. In most cases, of course, this would result in instability. But, it turns out, my Q9100 was stable under several hours of OCCT testing at minimum VID (1.05V) at top multiplier (nominal VID 1.275V). This resulted in a 10C drop in peak OCCT CPU load tests, and a 6C drop in peak OCCT GPU load tests (down to 76C from 82C peak).

Getting the Best out of the MacBook Pro Retina 15 Screen in VMware Fusion

I make no secret of the fact that I am neither a fan of Apple nor a fan of virtualization. But sometimes they make for the best available option. I have recently found myself in such a situation. My current employer, mercifully, allows employees a choice of something other than vanilla Windows machines to work on, and there was an option of getting a MacBook Pro. As you can probably guess from some of the previous articles here, I find the single most important productivity feature of a computer to be the screen resolution, an opinion I appear to share with Linus Torvalds. So I opted for the 15″ MacBook Pro Retina.

Unfortunately, the native Linux support on that machine still isn’t quite perfect. Since speed is not a concern in this particular case, I opted to run Linux using VMware Fusion on OSX. Unfortunately, VMware Fusion cannot handle full 2880×1800 resolution of the display and with lower resolutions running in full screen mode the quality is badly degraded by blurring and aliasing. The solution is to create a custom 2880×1800 mode in /etc/X11/xorg.conf that fits within VMware virtual graphic driver’s capabilities. This took a bit of working out since the mode had to fit within horizontal and vertical refresh rates of the driver and the total pixel clock the driver allows. The following are the settings that work for me:

Section "Monitor"
        Identifier "MacBookPro"
        HorizSync 30.0 - 90.0
        VertRefresh 30.0 - 60.0
        ModeLine "2880x1800C" 358.21 2880 2912 4272 4304 1800 1839 1852 1891

Section "Screen"
        Identifier "Default Screen"
        Monitor "MacBookPro"
        DefaultDepth 24
        SubSection "Display"
                Modes "2880x1800C"

The result is being able to run a full screen 2880×1800 mode, and it looks absolutely superb.

RedSleeve Linux Public Alpha

Here is something that I have been working on of late.

RedSleeve Linux is a 3rd party ARM port of a Linux distribution of a Prominent North American Enterprise Linux Vendor (PNAELV). They object to being referred to by name in the context of clones and ports of their distribution, but if you are aware of CentOS and Scientific Linux, you can probably guess what RedSleeve is based on.

RedSleeve is different from CentOS and Scientific Linux in that it isn’t a mere clone of the upstream distribution it is based on – it is a port to a new platform, since the upstream distribution does not include a version for ARM.

The reason RedSleeve was created is because ARM is making inroads into mainstream computing, and although Fedora has supported ARM for a while, it is a bleeding edge distribution that puts the emphasis on keeping up with the latest developments, rather than long term support and stability. This was not an acceptable solution for the people behind this project, so we set out to instead port a distribution that puts more emphasis on long term stability and support.

Alleviating Memory Pressure on Toshiba AC100

After all the upgrades and tweaks to the AC100 (screen upgrade to 1280×720, cooling improvements and boosting the clock speed by over 40%), only one significant issue remains: it only has 512MB of RAM. Unfortunately, the memory controller initialization is done by the closed-source boot loader, so even if we were to solder in bigger chips (Tegra2 can handle up to 1GB of RAM), it is unlikely in the extreme that it would just work.

So, other than increasing the physical amount of memory, can we actually do anything to improve the situation? Well, as a matter of fact, there are a few things.

Clawing Back Some Memory

By default, the GPU gets allocated a hefty 64MB of RAM out of 512MB that we have. This is quite a substantial fraction of our memory, and it would be nice to claw some of it back if we are not using it. I find the Nvidia’s Tegra binary accelerated driver to be too buggy to use under normal circumstances, so I use the basic unaccelerated frame buffer driver instead. There are two frame buffer allocations on the AC100: the internal display and the HDMI port. The latter is only intended for use with TVs which means we shouldn’t need a resulition of more than 1920×1080 on that port. The highest resolution display we can have on the internal port is 1280×720. That means that the maximum amount of memory used by those two frame buffers is 8100KB + 3600KB 11700KB. To be on the safe side, let’s call that 16MB. That still leaves us 48MB that we should be able to safely reclaim. We can do that by telling the kernel that there is extra memory at certain addresses using the following boot parameters:

mem=448M@0M mem=48M@464M

Make sure the accelerated binary Tegra driver is disabled in your xorg.conf, reboot and you should now have 496MB of usable RAM instead of 448MB. It’s just over an extra 10%, which should make a noticeable difference given how tight the memory is to begin with.

If you aren’t using the HDMI interface, my tests show that it is in fact possible to reduce the GPU memory to just 2MB with no ill effects, when using the 1280×720 display panel, because the frame buffer seems to operate in 16-bit mode by default:

mem=448M@0M mem=62M@450M

That leaves a total of 510MB of for applications.

Memory Compression

In the recent kernels, there are two modules that are very useful when we have plenty of CPU resources but very little memory – just the case on the AC100. They are zcache and zram. On the 3.0 kernels instead of zram we can use frontcache which is similar but has the advantage that it is aware and cooperates with zcache. Since at the time of writing this 3.0 isn’t quite as polished and stable for the AC100 as 2.6.38, let’s focus on zram instead.

Assuming you have compiled zcache support into your kernel, all you need to do to enable it is add the kernel boot paramter “zcache”. From there on, your caches should be compressed, thus increasing the amount they can store.

zram provides a virtual block device backed by RAM, but the contents are compressed, so it should always end up using less than the amount of memory it presents as a block device (unless all of the data is uncompressible, which is very unlikely). To err on the side of caution we shouldn’t set this to more than half of the total memory across all the zram devices. To ensure optimal performance, we should also set the number of zram devices to be the same as the number of CPUs cores in the system to make sure that all CPUs end up being used (each zram device handler is a single thread).

To set the number of zram devices to 2 (Tegra2 has 2 CPU cores), we need to create the file /etc/modprobe.d/zram.conf containing the following line:

options zram num_devices=2

Then once we load the zram module (modprobe zram), we should see device nodes called /dev/zram*. We can configure the devices:

echo > /sys/block//disksize

The amount of memory assigned to each zram device should be such that their total combined size doesn’t exceed half of the total physical memory in the system.

Then we can create swap headers on those zram devices using mkswap (e.g. mkswap /dev/zram0) and enable swapping to them (swapon -p100 /dev/zram0).

We should now have some compressed RAM for swapping to instead of swapping to a slow SD card.


It turns out that some of the default settings on Linux distributions aren’t as sensible as they could be. By default the amount of stack space each thread is allocated is 8MB. This is unnecessarily large and results in more memory consumption than is necessary. Instead we can set the soft limit to 256KB using “ulimit -s 256”. Ideally we should make this happen automatically at startup by creating a file /etc/security/limits.d/90-stack.conf containing the following:

* soft stack 256

Some users have reported that this can increase the amount of available memory after booting by a a rather substantial amount. Since this is a soft limit, programs that require more stack space can still allocate it by asking for it.

Choice of Software

One of the most commonly used types of software nowdays is a web browser, and unfortunately, most web browsers have become unreasonably bloated in recent years. This is a problem when the amount of memory is as limited as in it is on most ARM machines. Firefox and to a somewhat lesser extent Chrome require a substantial amount of memory. However, there is another reasonably fully featured alternative that works on ARM – Midori. Midori is based on the Webkit rendering engine, the same one that is used by Chrome and Safari. However, it’s memory footprint is approximately half of the other browsers. Unfortunately, it’s JavaScript support isn’t quite as good as on Firefox and Chrome yet, but it is sufficiently good for most things, and if memory pressure is a serious issue, you might want to try it out.