Linux kernel version in Android

[Neo]

What is the latest linux kernel available in Android source, looks
like its is 2.6.27? How can I download Android source with linux
kernel 2.6.24?


Thanks,
Neo

[Greg KH]

You can't.

And why would you want to do such a thing, 2.6.24 is a few years old now,
right? Using older kernel versions like that is not a good thing to do.

good luck,

greg k-h

[Neo]

On May 27, 12:47 am, Greg KH <gre...@gmail.com> wrote:

> On Mon, May 25, 2009 at 1:39 AM, Neo <zingafri...@yahoo.com> wrote:
>
> > What is the latest linux kernel available in Android source, looks
> > like its is 2.6.27? How can I download Android source with linux
> > kernel 2.6.24?
>
> You can't.
>
> And why would you want to do such a thing, 2.6.24 is a few years old now,
> right?  Using older kernel versions like that is not a good thing to do.
>
> good luck,
>
> greg k-h

Well, maybe 2.6.24 is old but that's the latest we have. Is there a
way around?
We have our patches to be taken care of so what is the best way to get
Android specific patches form the source, which version of linux
kernel should I diff it with for getting patches?

[Greg KH]

On Thu, May 28, 2009 at 9:28 PM, Neo <zinga...@yahoo.com> wrote:
> On May 27, 12:47 am, Greg KH <gre...@gmail.com> wrote:
>> On Mon, May 25, 2009 at 1:39 AM, Neo <zingafri...@yahoo.com> wrote:
>>
>> > What is the latest linux kernel available in Android source, looks
>> > like its is 2.6.27? How can I download Android source with linux
>> > kernel 2.6.24?
>>
>> You can't.
>>
>> And why would you want to do such a thing, 2.6.24 is a few years old now,
>> right?  Using older kernel versions like that is not a good thing to do.
>>
>

> Well, maybe 2.6.24 is old

Very old. Hundreds of thousands of kernel changes old. Do you really realize
how old it is?

> but that's the latest we have.

Who is "we" here? Why can't you use a newer kernel version? What is keeping
you from updating? Out-of-tree kernel drivers? If so, where are they, I will
be glad to forward port them for you and get them into the main kernel tree.

> Is there a way around?

As this seems to be a self-inflicted requirement, it seems that you would be
the only one to be able to resolve this. You can't ask the community to do
backporting work for you.

> We have our patches to be taken care of

Where are these patches?

> so what is the best way to get Android specific patches form the source,
> which version of linux kernel should I diff it with for getting patches?

Just do a diff on the git tree, it makes it very trivial to do so.

good luck,

greg k-h

[Neo]

On May 29, 8:31 pm, Greg KH <gre...@gmail.com> wrote:

> On Thu, May 28, 2009 at 9:28 PM, Neo <zingafri...@yahoo.com> wrote:
> > On May 27, 12:47 am, Greg KH <gre...@gmail.com> wrote:
> >> On Mon, May 25, 2009 at 1:39 AM, Neo <zingafri...@yahoo.com> wrote:
>

> >> > What is the latestlinux kernelavailable in Android source, looks

> >> > like its is 2.6.27? How can I download Android source withlinux>> > kernel2.6.24?
>
> >> You can't.
>
> >> And why would you want to do such a thing, 2.6.24 is a few years old now,
> >> right?  Using older kernel versions like that is not a good thing to do.
>
> > Well, maybe 2.6.24 is old
>
> Very old.  Hundreds of thousands of kernel changes old.  Do you really realize
> how old it is?
>
> > but that's the latest we have.
>
> Who is "we" here?  Why can't you use a newer kernel version?  What is keeping
> you from updating?  Out-of-tree kernel drivers?  If so, where are they, I will
> be glad to forward port them for you and get them into the main kernel tree.
>
> > Is there a way around?
>
> As this seems to be a self-inflicted requirement, it seems that you would be
> the only one to be able to resolve this.  You can't ask the community to do
> backporting work for you.
>
> > We have our patches to be taken care of
>
> Where are these patches?
>
> > so what is the best way to get Android specific patches form the source,

> > which version oflinux kernelshould I diff it with for getting patches?

>
> Just do a diff on the git tree, it makes it very trivial to do so.
>
> good luck,
>
> greg k-h

Greg, I appreciate your comments.
I am sorry to bother with trivial questions but I am a hardware guy
and not an OS person and hence am new to this. I want to use Android
in our work but as I said our patching work is stuck at 2.6.24. I saw
the GIT repository for android and it has kernels from still earlier.
So if I am correct I have two options-
(i) Use the android 2.6.24 kernel and download other platform related
code from the git and see if it builds, this is certainly hopeless I
feel, or
(ii) Use the latest stable release of Android and port our changes to
that kernel. This is feasible but very time consuming I think.

Let me know if what I have deduced is correct. Does it mean that one
cannot download Android sources for some specific kernel version like
2.6.24 or 2.6.27 or 2.6.29? Wouldn't it have been very useful if it
was possible?

Thanks,
Neo

[Greg KH]

On Sun, May 31, 2009 at 9:38 PM, Neo <zinga...@yahoo.com> wrote:
> I am sorry to bother with trivial questions but I am a hardware guy
> and not an OS person and hence am new to this. I want to use Android
> in our work but as I said our patching work is stuck at 2.6.24. I saw
> the GIT repository for android and it has kernels from still earlier.

That is because it is based off of the upstream kernel.org tree. It
also has 2.6.13 in the tree to, that doesn't mean android works on it :)

> So if I am correct I have two options-
> (i) Use the android 2.6.24 kernel and download other platform related
> code from the git and see if it builds, this is certainly hopeless I
> feel, or

It would require a lot of backporting of code, a non-trivial ammount of
work.

> (ii) Use the latest stable release of Android and port our changes to
> that kernel. This is feasible but very time consuming I think.

No, not at all, that is what you should do, as it will provide you a
path for the future. What happens when android moves to 2.6.29?
2.6.32? Will you continue to backport to an old, unsupported, buggy,
and insecure kernel version like 2.6.24? I hope not.

> Let me know if what I have deduced is correct. Does it mean that one
> cannot download Android sources for some specific kernel version like
> 2.6.24 or 2.6.27 or 2.6.29? Wouldn't it have been very useful if it
> was possible?

No, many tens of thousands of changes have gone on between those kernel
versions, it is better for you to get your changes into the main kernel
tree, or upgrade yourself.

Again, if you need help forward porting your kernel changes to the
latest kernel and getting the code into the tree, please let me know, we
can do that work.

Also, what specifically is keeping you at the 2.6.24 kernel release?
What changes have you made that requires such an old and obsolete
kernel?

thanks,

greg k-h

[Elvis Dowson]

Hi,

       The latest kernel version is android-2.6.29. There are a lot of differences between 2.6.27 and 2.6.29 itself. In general, you should consider support for the processor platform that you selected. For example, I am using a TI OMAP 35x series processor. Even with android kernel 2.6.29, power management is not yet fully supported in this kernel version. But for older processors, it would be. 

Elvis

[Neo]

Thanks for your replies.

The present kernel version is still 2.6.27 because that what it says
in the manifest.xml if I am correct, though development is happening
on 2.6.29 even 2.6.30.
Will the Android build scream if I point to a different(2.6.28) kernel
version in the manifest.xml? or should I clone the entire kernel/
common project and build with that path in the makefile?

[Elvis Dowson]

Hi,

      Even though the 2.6.27 kernel is present in the android distribution, I didn't use it much. The only thing to keep in mind is that bionic requires some header files so that it can link into the actual kernel libraries at run-time. 

So, I've done a 2.6.29 port, and built android userland which had kernel 2.6.27. However, towards the end, for some modifications due to the new DSS2 subsystem (for the LCD display), I had to update the bionic libraries to use the 2.6.29 kernel headers.

Elvis

[Neo]

It appears that the emulator in android run on a pre-built kernel
available in prebuilt/android-arm/kernel.
I tried built the kernel separately with 2.6.29 sources in the repo
but it failed to boot on the emulator and
says "warning: opening audio input failed".
The same thing happened with 2.6.28 also, are these not expected to
work on emulator?

[bhoj]

Hello Everyone,

I too am in a similar situation. I have a 2.6.24 kernel.I plan to port
the drivers to 2.6.27 android kernel.

I am new to kernel development.My basic understanding is porting the
timers,serial,I2c would be an easy task.Please warn me if I am wrong.

I want to know what are the architectural changes in 2.6.24 and 2.6.27
which could affect the drivers.

How difficult could it be for porting these drivers
audio,video,usb,mmc from 24 kernel to 27.


Thanks in advance,

Vishal


On Jun 1, 7:39 pm, Greg KH <gre...@gmail.com> wrote:

[Greg KH]

On Thu, Jun 11, 2009 at 11:18 PM, bhoj<visha...@gmail.com> wrote:
>
> Hello Everyone,
>
> I too am in a similar situation. I have a 2.6.24 kernel.I plan to port
> the drivers to 2.6.27 android kernel.
>
> I am new to kernel development.My basic understanding is porting the
> timers,serial,I2c would be an easy task.Please warn me if I am wrong.

Yes, it is easy if you know what changes are needed to be done :)

Why not port to .29 instead of the obsolete .27 kernel?

> I want to know what are the architectural changes in 2.6.24 and 2.6.27
> which could affect the drivers.
>
> How difficult could it be for porting these drivers
> audio,video,usb,mmc from 24 kernel to 27.

There have been tens of thousands of kernel changes between those two
versions. Do you have a pointer to your drivers to see how much work this
would entail?

Why are the drivers not already in the main kernel source tree? If they were,
they would have been automatically ported for you.

thanks,

greg k-h