SMP-enabled kernel for OLPC XO-4
I had known even before I received the laptop over a year ago that the Marvell Armada PXA2128 Soc used in XO-4 featured a dual-core CPU, but for some reason the kernel didn't support that.I recently got tipped by forum member mavrothal, my partner in development of FatdogArm for the OLPC, that the OLPC kernel for XO-4 finally got dual-core capability, who had built the latest git master from the kernel and got SMP kernel working.
I didn't have the time back then, but yesterday I finally got the chance to play with it. I built the kernel myself too, and I needed to update the OFW firmware to at least q7c04 for the dual-core kernel to run, but everything is smooth - new kernel booted and worked flawlessly with both cores enabled. All the existing functionalities continue to work, but the rc.platform will require a little patch because the ID code that I used to identify XO-4 has changed.
I will upload the new kernel, with update instructions (mainly pointing back to OLPC on how to update the firmware etc), and a new FatdogArm sfs with the required rc.platform change.
It has been a long time since the last FatdogArm beta2 release, so I may as well update some of the other packages too and call it beta3. Watch this space for further announcement.
After updating the OLPC firmware, the old original Fedora/Sugar in XO-4 will stop running. The fix is to download a newer build of the OS and install it to the laptop.
I need to say that I continue to be impressed and amazed of how OLPC implements these processes (both updating firmware and updating the internal OS). They are simple, easy, foolproof and very informative.
This is a far cry from similar processes of other commercial offerings. Especially since I had to deal with UEFI recently - if only UEFI implements half of what OLPC does with its Open Firmware, it would have been immensely more useful. Something's got to be better than BIOS, but UEFI isn't the one - OpenFirmware certainly is.
I applaud the engineering that went into the design and implementation of these features. There must have been a lot of thinking, and a lot of effort to examine of how the processes on standard PC broke down or failed in one way or another - and they made it really better.
This is of course on top of other excellent features of OLPC laptop - and I don't even mean the advertised educational benefits - but things like physical robustness, ease of maintenance, quality selection and durability of its components. Sure, this does not make it the lowest cost laptop (or even a lower cost tablet), but quality has its price and an investment of an OLPC laptop will far out-weight its cost and last far longer than any other laptops (or tablets) designed for similar purposes.
Personal note - I still think that a laptop is a far more useful for education than a tablet, regardless of the recent fad. If you are a decision maker and considering to get some sort of tablets or OLPC laptops, I'd highly recommend you go with OLPC XO-4. As a bonus, an XO-4 with touch screen (XO-4 touch) can function as a tablet too - just flip its screen. That is how versatile it is.
Disclaimer: I am saying all the above not because I am affiliated with OLPC (the only indirect relationship I have with OLPC is that I am doing a non-commercial community project for the OLPC XOs - that is, FatdogArm). I really like the OLPC laptop, I really like OLPC mission, and I really wish and hopeful that OLPC as an organisation will succeed and continue to focus on these quality offerings.
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Dual-boot Windows/Linux on Sony laptop with UEFI and Secure Boot
I haven't written an article for a very long time, so here is one: Dual-boot Windows/Linux on Sony laptop with UEFI and Secure BootComments - Edit - Delete
xannonate/xscreenshot updated
Minor update to xannotate/xscreenshot: the hotkey can now be given in either symbolic form (e.g. "Print") or in numeric form (107). This is necessary because sometimes the same key name (e.g. Print) can have multiple key codes (e.g. 107, 218); and hotkey selection inside X works based on keycodes. I found this out because the "Print" button on my (newish) laptop doesn't work; it turns out that this particular laptop dish out 218 for the Print button; while the standard mapping is 107 (which gets used), so as far as the program is concerned it never gets triggered.As a convenience, if you give it a numeric keycode, it will try to find the other standard keycode that represents the same key, and grab it too.
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Fatdog64 700 is released
Linux 3.18.7 and many enhancements and bug fixes over the 700rc release.Release notes
Forum announcement
Get it as usual from ibiblio or one of its mirrors: aarnet, uoc.gr, and nluug.nl.
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Fatdog64 700rc Release
Linux 3.18.6, Seamonkey 2.32, flash player 11.2.202.442 and other bug fixes.Release notes
Forum announcement
Get it as usual from ibiblio or one of its mirrors: aarnet, uoc.gr, and nluug.nl.
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Maximum size of initramfs
Well, I'm still around
.
Just want to document this often asked problem: what is the maximum size allowed, for an initramfs? Obviously this will be related to how much RAM you have, but what is exactly the relationship?
I have answered the question here, but I didn't explain why the numbers are what they are. This post attempts to correct that, if you're interested.
When considering this question, there are two things to remember:
a) initramfs will be uncompressed to memory during boot-up, so the amount of RAM needed would be the size of the initial initramfs + size of uncompressed initramfs
b) how much RAM the kernel will want to allocate for holding initramfs.
For the system to successfully boot, (a) must be the same or less than (b).
(a) is easy - by rule of thumb, it is twice the uncompressed size of initramfs. It is exact for uncompressed initramfs, and approximate for compressed initramfs; in either way it will give you the upper bound.
(b) is a bit more complicated. Traditionally the kernel will use "ramfs" for initramfs (that's why it is called init-ramfs ...
), and it will happily allocate all of your RAM for it, which is unwise, so you should at least subtract about 0.5GB from your RAM size if you want a usable system (unless your idea of fun is dealing with kernel OOM-killer that kills your important system services right after boot - not me).
But somewhere around kernel 3.x (circa 2012), the kernel merged "inittmpfs" patch from Rob Landley (of busybox and toybox and aboriginal Linux fame). It means that from that day onwards, initramfs will use "tmpfs" as opposed to "ramfs" by default (you can still switch back to using ramfs by specifying "rootfstype=ramfs" on your kernel command line). In case you're not familiar with the difference, "tmpfs" is "ramfs" with a size-limit (among others); and by default the limit is 50% of your RAM.
But wait, you say, doesn't "tmpfs" come with knobs to specify the maximum size? Yes, it does, but not at boot-time, no. Sure, you can re-mount it and changes it size, but we're talking here the situation during initramfs loading, *before* any code in initramfs itself is started ...
Rob actually has a patch to do exactly this, using "rootfsflags", but don't count on it going to mainline kernel soon.
But I digress. So, to come back to the subject, with "ramfs" you get all of your RAM (minus your 0.5GB), and with "inittmpfs" you get 50% of your RAM. This is (b). And since (a) is twice the size of your initramfs, it means that the maximum allowable size of your initramfs is 1/2 of (b).
Which means, if you use "inittmpfs" (which is the default in modern kernels), your initramfs size is limited to 1/2 of 50% of your RAM, or 25% of your RAM. If you use "ramfs" by specifying "rootfstype=ramfs" in your kernel boot command line, when this limit can increase to 1/2 of your RAM (minus 0.5GB), or, about 40%-45% of your RAM (depending on how big it is). Q.E.D.
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Fatdog64 700 beta2 is released
Linux 3.17.1 and other updates, fixes problem with missing fonts on opera/chrome and others.Release notes
Forum announcement
Get it as usual from ibiblio or one of its mirrors: aarnet, uoc.gr, and nluug.nl.
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FatdogArm Beta2 sfs re-uploaded
The main change is that xorg-server is now built with these two patches: http://forum.odroid.com/viewtopic.php?p=37553&f=7#p37553 and http://forum.odroid.com/viewtopic.php?p=35833&f=7#p35833 for better performance and stability. Thanks Daniel (aka dsd). This change only improves Odroid, and has no impact in other platforms as only Odroid uses DRI2 interface at the moment (Allwinner: fbdev, OLPC/Marvell: DRI1, Cubox-i/Freescale: DRI1).Coupled with a few updates in the repo and youtube-dl, it is now possible to write a simple script that will stream video and play it fullscreen on Odroid/Cubox-i directly from youtube. Perhaps I'll share that script later.
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3D hardware acceleration for cubox-i
I have finally managed to get 3D acceleration working on cubox-i. This has been long-time coming.Initial testing of the 3D acceleration always caused a hard lock-up on Xorg. System was still alive, and was still responsive (if you use SSH), but Xorg completey died, you can't even switch VT anymore.
Today I have finally found the solution - Freescale provided a patch for libdrm, *and* Xorg must be re-compiled against this patched libdrm. This was found as early as March by forum member "notwa", but I didn't take this seriously because:
a) it was intended for kernel 3.0.35 while I used 3.10.30 kernel
b) I actually patched libdrm but didn't rebuild xorg-server as I thought it was unnecessary (I reviewed xorg-server source to find where exactly the patched change could have impact, and couldn't see it).
Today I found that another forum member "catwich" had the same problem I had, and confirmed that "notwa" solution worked - if followed in full. I decided to have a go myself on FatdogArm, and look and behold - it worked! es2gears, glmark2 and glmark2-es2 all worked. What a joy!
The updated drivers will be in the repository as usual. As a closing note, I also built gst-plugins-gl (containing "glimagesink" - see my earlier post about hardware accelerated video playback pipeline), and it works well as an alternative to mfw_v4lsink.
With this, support for cubox-i platform is now considered complete (apart from bluetooth support, but that's minor stuff ... may be later). All these work with FatdogArm beta2. I updated the release note to reflect this fact but if you have already downloaded the SFS and the kernel package, there is no need to download again as there is no change there: all the drivers are in the repository and those are the ones that got updated.
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Hardware-accelerated video playback on Odroid U2/U3 - part 2
Near the end of my previous post, I said that while the video playback was decent, it was not as smooth as expected, and that "memeka" from the odroid forum suggested to use cluttersink instead of glimagesink.I have now built and tested cluttersink, and indeed cluttersink shows smoother playback than glimagesink. There is one small difference: cluttersink doesn't respect aspect ratio, it will just scale up everything to its window size; while glimagesink does honour aspect ratio (but you can disable it if you don't need it).
Here is an example pipeline that plays an mp4 file, both audio and video, with full video acceleration using cluttersink:
gst-launch-1.0 filesrc location=/path/to/media.mp4 ! qtdemux name=m m. ! queue ! h264parse ! video/x-h264, stream-format=byte-stream, alignment=au ! v4l2video8dec ! v4l2video10convert ! cluttersink m. ! queue ! faad ! audioconvert ! alsasinkThe same pipeline, simplified using decodebin:
gst-launch-1.0 filesrc location=/path/to/media.mp4 ! decodebin name=m m. ! queue ! v4l2video10convert ! cluttersink m. ! queue ! audioconvert ! autoaudiosinkcluttersink is available in "gst2-clutter" package in the repository.
I also re-uploaded Odroid U2/U3 kernel package for FatdogArm Beta2, now with MFC firmware (which is needed for hardware acceleration). Thanks to forum member "mories" who informed me that I forgot to do that. Beta2 sfs is also re-uploaded, now with updated glib (2.38.2 now, it was 2.36.3 previously) which is needed for cluttersink and its libraries, among other small fixes.
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