General questions about Linux
 

With all of the talk lately about Maemo and Andriod and other Linux based OSes, I just had a few newbie questions.

Is Linux technically an OS or a type of computer language, since there are so many different Linux distros?

If Linux is an OS, then how is it that there are so many different kindsof Linux distros? And on that note, what is the difference between Debian, Symbian, Maemo, and Android, since they are all based on the same Linux?

If a device has one OS, is it possible to install another different OS on there (ie. Motorola Droid comes with Android, can it be flashed to run Maemo)? If not, why is that?

I've been reading up on the Maemo vs. Android debate and a recurring theme is that Maemo is more "open." How is Maemo more "open" when both Android and Maemo are Linux based, which is completely open?

Lastly, how is it possible that Linux is capable of running on both x86 architecture devices and ARM architecture devices? Isn't the x86 and ARM instruction set completely different? And if I'm not mistaken, Linux is also used in PowerPC machines too.

Thanks for your help!:)

Re: General questions about Linux
 

Linux refers to the kernel which all Linux distributions have in common. It's pretty much the ground or basement floor of any device that uses Linux (TIVO, Linux distributions, etc..).

As pointed out above, Linux is simply the kernel. Distributions are the GUI and tools that interface with the kernel. The difference is in the GUI, and tools offer.

No, you need drivers for one thing. And then there's the bootloader (depending on if it's locked down). Not to mention Maemo has closed source components. Mer on the other hand might be possible with drivers.

Things like root are locked out on Android. Thus if you want to do anything that requires root (administrator permissions basically) you can't do it on Android without hacking about. That's just one example.

Yes the instruction sets are different, it just happens that the kernel is very versitile when it comes to being brought to many platforms after a recompile.

Re: General questions about Linux
 

Was just writing a response but Laughing Man beat me to it.

Only things to add are that Symbian is based on EPOC not Linux, and that while Android utilises the Linux kernel it does not use the same GNU libraries as most Linux distros.

http://www.linux.com is a good place to start if you want to find out about Linux.

Re: General questions about Linux
 

Linux is only a operating system kernel; linux distributions are complete systems containing linux kernel and many other software packages (e.g. desktop interfaces, web browsers) http://en.wikipedia.org/wiki/Linux_distribution

They all contain different set of preinstalled software, are targeted towards other use-cases (symbian ain't linux :)), contain somehow different configuration tools... This is too wide and flameable topic... .)

Though it's not currently too common, it could be possible in near future - the same way e.g. linux is able to run on most of hardware windows can run on... I've run linux minidistro and android (which is basically linux kernel + java-like GUI on top) on my win-mobile device recently :) no phone functionality just yet though...

there is too much discussion about this on the internet - use google ;)

it's all about coding style - once you write portable code (which is very common in open source development), the porting to other architecture is as simple as compiling C code with different compiler... of course, there is some architecture-depedent stuff in the kernel, but huge parts of it are platform-independent...

Re: General questions about Linux
 

But if the Linux kernel is completely open, how can Google lock out the root? Isn't that against the open-source nature of Linux?

I can see Nokia's incentive for creating Maemo for its own devices, but what incentive does Google have for creating Android, since they technically don't build their own phones? If they are charging OEMs for Android, isn't that also against the free and open source nature of Linux?

If Android does lack the root feature, how are people able to write apps for it? Since Maemo is more open than Android, I'm pretty surprised that Android seems to be taking off more so than Maemo is. Aside from Android being backed by Google, are there any other reasons why it is more prevalent in new devices (ie. why aren't others adopting Maemo)?

Thanks again for the great info guys!:D

Re: General questions about Linux
 

The reason I'd prefer Maemo to Android (regardless of whether this has to do with openness or not) is the fact that Android is its own special environment on top of the Linux kernel, while Maemo is much more like a regular Linux distro.

I think the GNU parts of a Linux distro are important. Infact, maybe one should call it GNU/Linux, when referring to the operating system as a whole and not just the kernel... :)

Re: General questions about Linux
 

Against the spirit yes, but not the law.

They are getting money from vendors via unspecified means (or they could be paying money, we don't know), however companies like Redhat and SuSE charge for their distros as well. This is not against the spirit or law of open-source. Despite not making hardware, Google gets a lot from it, especially if the devices come with Google's applications.

Android apps are written using Java and the Android software development kit, which runs on your desktop PC. You can then load applications on an SD card and install them, or install them over the internet. It's actually quite easy. Android is getting a lot of attention because it has been out for a year, has a number of phones, and has Google backing it.

Re: General questions about Linux
 

I'm sure Android on its own, can be pretty open too, but maybe they can lock it down that way for particular phones/carriers, while Nokia will give the user root for Maemo 5 out of the box?

One reason Android is growing more than Maemo at the moment is probably that there are plenty of phones that run it and has been for some time, while the N900 is the first Maemo phone, the first Maemo 5 device and was just (barely) released.

Re: General questions about Linux
 

They just make it hard to access (or change the root password). And yes it's slightly against the open-source nature of Linux (hence why some people prefer Maemo to Android simply for it being more open).

Google just wants people to use their services. An operating system built around their services gets more people using their services. Hence also why you see Google stuff on Symbian, BlackBerries, Windows Mobile, etc.. they don't care if people use Android or not as long as you use their services.

And there's nothing that says you can't charge for Linux. It's just under the GPL you have to provide the source code (meaning anyone could also recompile it and distribute it).

It doesn't lack root necessarily, you can hack it back onto there. Just like you can jailbreak an iPhone. It's more "why should we have to jump through these loopholes". Android can also go on any device (from non-touch screens, to touchscreens, to tablets, to netbooks, etc..). Nokia is currently keeping Maemo to themselves. Mer on the other hand is the more open sourced version of Maemo.

Re: General questions about Linux
 

You are using the wrong sense of the word 'free'. Do you speak French at all? 'free' in open source terms is 'libre' in French, not 'gratuit'. In English the usual comparison is 'free as in speech. not as in beer'.

Android is free in that anyone can download and compile their own version of Android and can distribute that version as they wish. If you use one of those distributions of Android you can have root access on the phone if you wish. Manufacturers are free (i.e. at liberty) to install Android on their phones whether or not they pay Google anything.

However, although the operating system is free, some of the applications are not. If you distribute your own version of Android you have to omit or substitute some of Google's applications. One of the non-Google distributors of Android (cyanogen) recently ran into trouble because he was including Google's closed-source applications in his distribution. The most obvious missing link if you don't use a Google distribution is the marketplace app: you can still install software without it, but you cannot install paid applications.

That may not be a problem if you are a phone manufacturer: just have your own version of the marketplace which only allows access to your own little walled garden of apps. That's probably quite appealing for some phone providers.

As to how they can do this:

All Android applications must be digitally signed. This allows other applications or servers to identify the author or the application (or rather the person who compiled it). Even if you have the source for Google's marketplace the servers will not identify a copy you compile as being a valid Google copy of the application, so it only gets to see the free apps.