Support for ARM940T core Samsung S3C2510A MCU under Linux

Support for ARM940T core Samsung S3C2510A MCU under Linux

[Arnd Bergmann]

On Saturday 19 March 2011, Geert Uytterhoeven wrote:
> On Sat, Mar 19, 2011 at 10:53, Madhavi Manchala <madhavi.linux@gmail.com> wrote:
> > I have one basic question about the architecture files in Linux
> > kernels. We have a board with Samsung S3C2510A MCU (ARM940T core)
> > which is a no-mmu based CPU. I heard that "there was not a lot of ARM
> > no-mmu support at the moment" from Ben Dooks.
> >
> > So, I started developing the architecture files for my Samsung
> > S3C2510A MCU (ARM940T core) by looking at the existing S3C2410A
> > (ARM920 core) architecture files. Is this my porting (developing the
> > architecture files) correct?
> >
> > How can I port the Linux on to my board which has a Samsung S3C2510A
> > MCU (ARM940T core) which is a NO-MMU based CPU?
> >
> > Please suggest me. It would be appreciated your help / suggestions.
> 
> I think the uClinux mailing list (CCed) is a more appropriate mailing list for
> your questions.

It depends. Any questions regarding the ARM kernel should be on the
arm-linux-kernel (also CCed now), since the nommu support is merged
with the mainline kernel.

uClinux seems to be rather focused on m68knommu (coldfire) these days,
and contains both a kernel and user space. The last uClinux release
containst some changes for Samsung platforms (s3c24a0, s3c3410,
s3c44b0x and s5c7375). It's probably a good idea to look at that
code for reference, but I would suggest integrating the code for
your platform in the upstream  tree directly.

I could not find a git tree for uClinux that contains any recent
kernel. Does that exist?

	Arnd

Support for ARM940T core Samsung S3C2510A MCU under Linux

[Greg Ungerer]

Hi Arnd,

On 20/03/11 06:14, Arnd Bergmann wrote:
> On Saturday 19 March 2011, Geert Uytterhoeven wrote:
>> On Sat, Mar 19, 2011 at 10:53, Madhavi Manchala<madhavi.linux@gmail.com>  wrote:
>>> I have one basic question about the architecture files in Linux
>>> kernels. We have a board with Samsung S3C2510A MCU (ARM940T core)
>>> which is a no-mmu based CPU. I heard that "there was not a lot of ARM
>>> no-mmu support at the moment" from Ben Dooks.
>>>
>>> So, I started developing the architecture files for my Samsung
>>> S3C2510A MCU (ARM940T core) by looking at the existing S3C2410A
>>> (ARM920 core) architecture files. Is this my porting (developing the
>>> architecture files) correct?
>>>
>>> How can I port the Linux on to my board which has a Samsung S3C2510A
>>> MCU (ARM940T core) which is a NO-MMU based CPU?
>>>
>>> Please suggest me. It would be appreciated your help / suggestions.
>>
>> I think the uClinux mailing list (CCed) is a more appropriate mailing list for
>> your questions.
>
> It depends. Any questions regarding the ARM kernel should be on the
> arm-linux-kernel (also CCed now), since the nommu support is merged
> with the mainline kernel.
>
> uClinux seems to be rather focused on m68knommu (coldfire) these days,

That is more a factor of who shows interest and is active on
the uclinux-dev mailing list more than anything else though.
Quite of few different groups of people interested in non-MMU
ARM platforms have shown up over the years, but none seem to stay
active for long.


> and contains both a kernel and user space. The last uClinux release
> containst some changes for Samsung platforms (s3c24a0, s3c3410,
> s3c44b0x and s5c7375). It's probably a good idea to look at that
> code for reference, but I would suggest integrating the code for
> your platform in the upstream  tree directly.

Yes, highly encourage this.


> I could not find a git tree for uClinux that contains any recent
> kernel. Does that exist?

I used to keep one on git.kernel.org for promoting non-architectural
but non-MMU specific changes to mainline.

http://git.kernel.org/?p=linux/kernel/git/gerg/uclinux.git;a=summary

But I have had so few changes that fit in that category that I
haven't used it in quite a while.

Regards
Greg


------------------------------------------------------------------------
Greg Ungerer  --  Principal Engineer        EMAIL:     gerg at snapgear.com
SnapGear Group, McAfee                      PHONE:       +61 7 3435 2888
8 Gardner Close                             FAX:         +61 7 3217 5323
Milton, QLD, 4064, Australia                WEB: http://www.SnapGear.com

Support for ARM940T core Samsung S3C2510A MCU under Linux

[Arnd Bergmann]

On Monday 21 March 2011, Greg Ungerer wrote:
> > I could not find a git tree for uClinux that contains any recent
> > kernel. Does that exist?
> 
> I used to keep one on git.kernel.org for promoting non-architectural
> but non-MMU specific changes to mainline.
> 
> http://git.kernel.org/?p=linux/kernel/git/gerg/uclinux.git;a=summary
> 
> But I have had so few changes that fit in that category that I
> haven't used it in quite a while.

Yes, I found that tree when I looked last week. I was wondering
if there is any git or other repo for the files that are in
http://sourceforge.net/projects/uclinux/files/uClinux%20Stable/

The kernel sources there are newer than the ones from uclinux.git,
but I could not find a pointer to who maintains them or how.

	Arnd

Support for ARM940T core Samsung S3C2510A MCU under Linux

[Greg Ungerer]

Hi Arnd,

On 21/03/11 22:20, Arnd Bergmann wrote:
> On Monday 21 March 2011, Greg Ungerer wrote:
>>> I could not find a git tree for uClinux that contains any recent
>>> kernel. Does that exist?
>>
>> I used to keep one on git.kernel.org for promoting non-architectural
>> but non-MMU specific changes to mainline.
>>
>> http://git.kernel.org/?p=linux/kernel/git/gerg/uclinux.git;a=summary
>>
>> But I have had so few changes that fit in that category that I
>> haven't used it in quite a while.
>
> Yes, I found that tree when I looked last week. I was wondering
> if there is any git or other repo for the files that are in
> http://sourceforge.net/projects/uclinux/files/uClinux%20Stable/
>
> The kernel sources there are newer than the ones from uclinux.git,
> but I could not find a pointer to who maintains them or how.

There is no git tree or otherwise for the code in the uclinux-dist
source package. It is just a random collection of patches collected
over the years, with new kernels "imported" every new release.

Regards
Greg


------------------------------------------------------------------------
Greg Ungerer  --  Principal Engineer        EMAIL:     gerg at snapgear.com
SnapGear Group, McAfee                      PHONE:       +61 7 3435 2888
8 Gardner Close                             FAX:         +61 7 3217 5323
Milton, QLD, 4064, Australia                WEB: http://www.SnapGear.com

Support for ARM940T core Samsung S3C2510A MCU under Linux

[Arnd Bergmann]

On Tuesday 22 March 2011, Madhavi Manchala wrote:

> These sources (patches) are similar to samsung sources which are
> available in uClinux-dist. So, I will look into the Ithamar Adema
> patches and uClinux-dist samsung machine directory sources. Please
> suggest me.
> 
> My final question, All these samsung machines (s3c24a0, s3c3410,
> s3c44b0x and s5c7375) are ARM7TDMI core based MCUs. My MCU (Samsung
> s3c2510A) is a ARM9TDMI core based. So, is this porting will help?

The CPU support is really separate from the platform, and
ARM9TDMI/ARM940T is supported by the platform-independent code.

In the s3c2510-specific portion, you should need very little
code that has dependencies on the specific ARM code besides
for the Kconfig 'select CPU_ARM940T' statement.

> I am extreamly sorry, If I asked silly questions here.

No problem at all, these things are not well documented, so it's
good if at least people can refer to this conversation in the
email archives.

	Arnd