avishorp
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Re: Which kernel

Tue Jan 17, 2012 4:13 pm

Hi

Does the Raspi require board support package or kernel patches?

Thanks,

Avishay

jamesh
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Re: Which kernel

Tue Jan 17, 2012 4:17 pm

You will be able to download a fully working OS image from the website. We expect other distro's to follow fairly quickly.
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mard0
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Re: Which kernel

Tue Jan 17, 2012 5:10 pm

Hmmmm i think this is a pretty interesting discussion. I'm confident that there will be a fully functioning kernel that will serve all you're desktopping and IT learning needs. But for the more hacking type among us it would be nice to have a patch wich you could apply to a custom or upstream kernel.

avishorp
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Re: Which kernel

Thu Jan 19, 2012 11:52 am

Off-the-shelf distribution is certainly not satisfying. I would like to compile my own (custom configured) kernel and system, and it's important to know if there are any board specific patches (or even worse, binary only kernel modules). If this is the situation, I would like to know what is the latest version supported.

jamesh
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Re: Which kernel

Thu Jan 19, 2012 12:18 pm

Avishay said:


Off-the-shelf distribution is certainly not satisfying. I would like to compile my own (custom configured) kernel and system, and it's important to know if there are any board specific patches (or even worse, binary only kernel modules). If this is the situation, I would like to know what is the latest version supported.


OTOH, it's completely satisfying to the vast majority of users.
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macemoneta
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Re: Which kernel

Thu Jan 19, 2012 12:30 pm

JamesH said:


Avishay said:


OTOH, it's completely satisfying to the vast majority of users.



The vast majority of Linux users?  I doubt that.  In any case, as Fedora is one of the distributions, I know that at least their kernel build process is well documented, including their patches.  Since they're basing their ARM distribution on the 3.2 kernel with Fedora 17, it's as current as upstream at the moment.

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Re: Which kernel

Thu Jan 19, 2012 12:33 pm

macemoneta said:


JamesH said:


Avishay said:


OTOH, it's completely satisfying to the vast majority of users.



The vast majority of Linux users?  I doubt that.  In any case, as Fedora is one of the distributions, I know that at least their kernel build process is well documented, including their patches.  Since they're basing their ARM distribution on the 3.2 kernel with Fedora 17, it's as current as upstream at the moment.


Absolutely. How many Linux users recompile the kernel for their own use on the desktop/server? Much less than 1%.
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macemoneta
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Re: Which kernel

Thu Jan 19, 2012 12:36 pm

JamesH said:


Absolutely. How many Linux users recompile the kernel for their own use on the desktop/server? Much less than 1%.


I'd like to see the source for that statistic.  :)

TheEponymousBob
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Re: Which kernel

Thu Jan 19, 2012 12:36 pm

macemoneta said:


JamesH said:


Avishay said:


OTOH, it's completely satisfying to the vast majority of users.



The vast majority of Linux users?  I doubt that.  In any case, as Fedora is one of the distributions, I know that at least their kernel build process is well documented, including their patches.  Since they're basing their ARM distribution on the 3.2 kernel with Fedora 17, it's as current as upstream at the moment.


... I'd say the vast majority of Raspberry Pi's targeted users.

macemoneta
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Re: Which kernel

Thu Jan 19, 2012 12:38 pm

TheEponymousBob said:


... I'd say the vast majority of Raspberry Pi's targeted users.


So no new kernel developers from the education system?

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Re: Which kernel

Thu Jan 19, 2012 12:48 pm

macemoneta said:


JamesH said:


Absolutely. How many Linux users recompile the kernel for their own use on the desktop/server? Much less than 1%.


I'd like to see the source for that statistic.  :)


I'd like to see the source for yours (which I presume states the opposite?). Mine's anecdotal, in that I know no-one who compiles their own kernel for their 'desktop' machine. For the simple reason that its unnecessary.
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jamesh
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Re: Which kernel

Thu Jan 19, 2012 12:49 pm

macemoneta said:


TheEponymousBob said:


... I'd say the vast majority of Raspberry Pi's targeted users.


So no new kernel developers from the education system?


Did you not see the phrase 'vast MAJORITY'?
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macemoneta
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Re: Which kernel

Thu Jan 19, 2012 12:52 pm

JamesH said:


I'd like to see the source for yours (which I presume states the opposite?). Mine's anecdotal, in that I know no-one who compiles their own kernel for their 'desktop' machine. For the simple reason that its unnecessary.


My equally anecdotal evidence is that I know several Linux users, about half of whom do their own kernel compiles for desktop use.  The primary reason is to get newer drivers, while I track the next release kernel to stay current with upstream.

When you buy a new gadget that you want to use, and it's not yet supported by your current kernel, your choice is to wait for the next release or compile one yourself.  Every major distribution provides end-user instructions for doing this.

mole125
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Re: Which kernel

Thu Jan 19, 2012 12:55 pm

Given that the wiki (http://elinux.org/Rpi_Low-leve.....eripherals) states:

The Foundation will not include a GPIO driver in the initial release, standard linux GPIO drivers should work with minimal modification.

The Foundation will not include a SPI driver in the initial release, we hope the community might write one.

The Foundation will not include an I2C driver in the initial release, we hope the community might provide one, standard linux I2C drivers should work with minimal modification.

I really hope that we can recompile the kernel else these will be hard to achieve.

I'm also expecting/hoping that people will write drivers to support attached peripherals (such as mobile phone screens, gps chips etc), to allow them to be used natively by X/standard linux programs rather than manually having to access them through low level GPIO operations.

That said I'd agree that most people won't need to but there will be sufficient people who will want to in order to support hardware mods or learn how compiling a kernel actually works.

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Re: Which kernel

Thu Jan 19, 2012 1:14 pm

macemoneta said:


JamesH said:


I'd like to see the source for yours (which I presume states the opposite?). Mine's anecdotal, in that I know no-one who compiles their own kernel for their 'desktop' machine. For the simple reason that its unnecessary.


My equally anecdotal evidence is that I know several Linux users, about half of whom do their own kernel compiles for desktop use.  The primary reason is to get newer drivers, while I track the next release kernel to stay current with upstream.

When you buy a new gadget that you want to use, and it's not yet supported by your current kernel, your choice is to wait for the next release or compile one yourself.  Every major distribution provides end-user instructions for doing this.


That's because you are in a group of Linux 'hackers' (for want of a better word), whereas I am in a group of Linux USERS. There are many more users than hackers. (note there is an intersection of the two groups)
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NRoach44
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Re: Which kernel

Thu Jan 19, 2012 1:30 pm

I compile my own kernel to slim down the file, and thus improve booting speeds. I can't right now though, because whenever 3.2.0 Installs, my modules (for virtual box and wifi) don't build properly. I amm downloading 3.2.1 to try though.

NRoach44
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Re: Which kernel

Thu Jan 19, 2012 1:31 pm

Oh, and it is "power users"

jamesh
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Re: Which kernel

Thu Jan 19, 2012 1:33 pm

NRoach44 said:


Oh, and it is "power users"


Thanks!
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macemoneta
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Re: Which kernel

Thu Jan 19, 2012 1:34 pm

JamesH said:


That's because you are in a group of Linux 'hackers' (for want of a better word), whereas I am in a group of Linux USERS. There are many more users than hackers. (note there is an intersection of the two groups)


Users become hackers when the need arises.  I provide end-user support at linuxquestions.org (for the last seven years).  Many users come looking for help getting some device working, and the solution is frequently updating to a newer kernel that has the support they need.  I point them to the documentation for their distribution, and help them with any problems they run into.  Even though they've never compiled anything in their lives, the process is usually successful.  Compiling a kernel, even when applying a vendor driver or patch, isn't difficult.  If you can bake a cake you can compile a kernel.

I don't see any reason this wouldn't be the same process on a Raspberry Pi.  There's nothing special about the kernel on the Pi, is there?

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Re: Which kernel

Thu Jan 19, 2012 1:40 pm

Nope. It's a standard Arm kernel build with the added driver for the GPU (and maybe another, can't remember). It's the rootfs that needs some extra libraries (the OGL, OVG ones for example) for acceleration.

When I need a new kernel on my desktop (pretty much never) I just get the latest one from Ubuntu. Fully tested, and working. Much easier. But then, I don't buy lots of gadgets I need to plug in. Just like most Raspi users I expect.
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Re: Which kernel

Thu Jan 19, 2012 1:54 pm

JamesH said:


Nope. It's a standard Arm kernel build with the added driver for the GPU (and maybe another, can't remember). It's the rootfs that needs some extra libraries (the OGL, OVG ones for example) for acceleration.

When I need a new kernel on my desktop (pretty much never) I just get the latest one from Ubuntu. Fully tested, and working. Much easier. But then, I don't buy lots of gadgets I need to plug in. Just like most Raspi users I expect.


I don't know if the distributions building for the Pi will be creating the full set of driver modules.  On Android, the module set is pared down to a pretty sparse set.  If a student wants to use something like a webcam or dvb-t dongle that isn't in the included set, a build will be needed.  Some older hardware, which may be available in someones junk box, is no longer built by default in some distributions.  In that case, just getting a different kernel from the distribution wont solve the problem.

Fedora already has kernel build instructions up for ARM, including how to setup the cross build toolchain on x86/x86_64 machines.  If anyone's interested, you can just point them to the Fedora ARM Wiki, here:  http://fedoraproject.org/wiki/.....ctures/ARM

avishorp
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Re: Which kernel

Thu Jan 19, 2012 2:26 pm

Most desktop users definitely use prebuilt distros and kernels. In the embedded world things are different. It is a common practice to compile kernel and entire systems in order to customize it to specific needs, and to cope with the limited resources (projects such as buildroot and openembedded are often used for this purpose).

Anyway, the question "why" is of little relevance - if kernel patches have to be applied in order to run it on the Raspi, they must be fully provided - this is a basic concept of the GPL license.

david13lt
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Re: Which kernel

Thu Jan 19, 2012 2:38 pm

Well, I am OpenEmbedded user and I do build custom kernels. Sometimes to have a need to modify, customize, tune the kernel, add new things, which yet are not available in mainline kernel. I would expect myself to building a custom kernel for R-P.

I would hope, that anything needed (patches, blobs, etc) to do so is provided by R-P.

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Re: Which kernel

Thu Jan 19, 2012 3:05 pm

Avishay said:


Most desktop users definitely use prebuilt distros and kernels. In the embedded world things are different. It is a common practice to compile kernel and entire systems in order to customize it to specific needs, and to cope with the limited resources (projects such as buildroot and openembedded are often used for this purpose).

Anyway, the question "why" is of little relevance - if kernel patches have to be applied in order to run it on the Raspi, they must be fully provided - this is a basic concept of the GPL license.


The Raspi is in effect a desktop, rather than an embedded system, but the point about patches is correct, they will need to be provided under the GPL. Well, you could provide a whole kernel tree rather than patches, which may be more appropriate for the target audience, but the point is the same.
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richard77
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Re: Which kernel

Thu Jan 19, 2012 9:21 pm

While creating the patches will have an higher initial amount of work, it should ease the maintenance of the kernel, i.e. it should be easier to port new kernels and modules to the R-Pi, with the long term goal to have them into mainline kernel.

That said, of course the Fundation has no unlimited resources, so it is a matter of priorities.

Anyway, to build modules generally only kernel headers are needed, not fully source.

For example, I would like to try zram/zcache to reduce ram usage and aufs to improve solid disk speed, but I would not recommend to use those feature in a standard setup.

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