Question on ARM Cortex R4 support in Linux

Question on ARM Cortex R4 support in Linux

[shiraz hashim]

Hi,

We plan to use Linux on our Cortex R4 based SoC.
Can we use the latest Linux straight away or do we
require to add some support for it.

I went through www.linux-arm.org/LinuxKernel/LinuxM3
which describes Cortex M3 support in Linux but was not
able to find any information on M4.

Has anybody used it on Cortex R4 based platform ?

-- 
regards
Shiraz Hashim

Question on ARM Cortex R4 support in Linux

[Catalin Marinas]

On Mon, Feb 13, 2012 at 10:49:18AM +0000, shiraz hashim wrote:
> We plan to use Linux on our Cortex R4 based SoC.
> Can we use the latest Linux straight away or do we
> require to add some support for it.
> 
> I went through www.linux-arm.org/LinuxKernel/LinuxM3
> which describes Cortex M3 support in Linux but was not
> able to find any information on M4.

Do you mean M4 or R4 here?

> Has anybody used it on Cortex R4 based platform ?

In theory Linux support for R4 should just work (once CONFIG_MMU is
disabled). I used to test it in the past regularly but not recently.

-- 
Catalin

Question on ARM Cortex R4 support in Linux

[shiraz hashim]

Hi Catalin,

On Mon, Feb 13, 2012 at 4:23 PM, Catalin Marinas
<catalin.marinas@arm.com> wrote:
> On Mon, Feb 13, 2012 at 10:49:18AM +0000, shiraz hashim wrote:
>> We plan to use Linux on our Cortex R4 based SoC.
>> Can we use the latest Linux straight away or do we
>> require to add some support for it.
>>
>> I went through www.linux-arm.org/LinuxKernel/LinuxM3
>> which describes Cortex M3 support in Linux but was not
>> able to find any information on M4.
>
> Do you mean M4 or R4 here?

I am interested in R4 but was just thinking that M4 support can work
for R4 as well.

>> Has anybody used it on Cortex R4 based platform ?
>
> In theory Linux support for R4 should just work (once CONFIG_MMU is
> disabled). I used to test it in the past regularly but not recently.

Great. I was planning to use linux-3.2, I hope the support is there ?

Thanks for the quick reply :)

-- 
regards
Shiraz Hashim

Question on ARM Cortex R4 support in Linux

[Catalin Marinas]

On Mon, Feb 13, 2012 at 10:59:50AM +0000, shiraz hashim wrote:
> Hi Catalin,
> 
> On Mon, Feb 13, 2012 at 4:23 PM, Catalin Marinas
> <catalin.marinas@arm.com> wrote:
> > On Mon, Feb 13, 2012 at 10:49:18AM +0000, shiraz hashim wrote:
> >> We plan to use Linux on our Cortex R4 based SoC.
> >> Can we use the latest Linux straight away or do we
> >> require to add some support for it.
> >>
> >> I went through www.linux-arm.org/LinuxKernel/LinuxM3
> >> which describes Cortex M3 support in Linux but was not
> >> able to find any information on M4.
> >
> > Do you mean M4 or R4 here?
> 
> I am interested in R4 but was just thinking that M4 support can work
> for R4 as well.

M4 and R4 are completely different processor classes. R4 is supported
pretty much by default in !MMU Linux as it's close to the A class (same
exception model). The M class has a completely different exception model
and it only supports the Thumb-2 instruction set.

> >> Has anybody used it on Cortex R4 based platform ?
> >
> > In theory Linux support for R4 should just work (once CONFIG_MMU is
> > disabled). I used to test it in the past regularly but not recently.
> 
> Great. I was planning to use linux-3.2, I hope the support is there ?

It's been there for years, but some bit-rotting may have occurred.

-- 
Catalin

Question on ARM Cortex R4 support in Linux

[Armando Visconti]

Ciao Catalin,


>>>> Has anybody used it on Cortex R4 based platform ?
>>>
>>> In theory Linux support for R4 should just work (once CONFIG_MMU is
>>> disabled). I used to test it in the past regularly but not recently.
>>
>> Great. I was planning to use linux-3.2, I hope the support is there ?
>
> It's been there for years, but some bit-rotting may have occurred.
>

I'm assuming you have tried it on a FPGA solution, is that correct?

We are planning to buy a Cortex-R4 board from ARM.
Lionel Belnet suggested to buy Versatile + a CoreTile with Cortex-R4F
r1p2 Test Chip on it.

Is there any Linux/ucLinux support already offered for this solution?
Any other idea?

Thx,
Arm


-- 
-- "Every step appears to be the unavoidable consequence of the
-- preceding one." (A. Einstein)
-- 
Armando Visconti                  Mobile: (+39) 346 8879146
Senior SW Engineer                Fax:    (+39) 02 93519290
CPG                               Work:   (+39) 02 93519683
Computer System Division          e-mail: armando.visconti at st.com
ST Microelectronics               TINA:   051  4683

Question on ARM Cortex R4 support in Linux

[Catalin Marinas]

On Mon, Feb 20, 2012 at 09:52:55AM +0000, Armando Visconti wrote:
> >>>> Has anybody used it on Cortex R4 based platform ?
> >>>
> >>> In theory Linux support for R4 should just work (once CONFIG_MMU is
> >>> disabled). I used to test it in the past regularly but not recently.
> >>
> >> Great. I was planning to use linux-3.2, I hope the support is there ?
> >
> > It's been there for years, but some bit-rotting may have occurred.
> 
> I'm assuming you have tried it on a FPGA solution, is that correct?

It may have been a real silicon (core tile for a RealView EB board), I
don't remember the details.

> We are planning to buy a Cortex-R4 board from ARM.
> Lionel Belnet suggested to buy Versatile + a CoreTile with Cortex-R4F
> r1p2 Test Chip on it.
> 
> Is there any Linux/ucLinux support already offered for this solution?

On www.arm.com/linux there is a uClinux tab with images for download,
though the kernel is 2.6.35. Anyway, you can always get a newer kernel
and just disable CONFIG_MMU for a RealView/EB board with ARMv6
processor.

> Any other idea?

I can't really tell what other R4 platforms are around.

-- 
Catalin

Question on ARM Cortex R4 support in Linux

[Armando Visconti]

Ciao Catalin,

Thx for the answer.

On 02/20/2012 11:01 AM, Catalin Marinas wrote:
> On Mon, Feb 20, 2012 at 09:52:55AM +0000, Armando Visconti wrote:
>>>>>> Has anybody used it on Cortex R4 based platform ?
>>>>>
>>>>> In theory Linux support for R4 should just work (once CONFIG_MMU is
>>>>> disabled). I used to test it in the past regularly but not recently.
>>>>
>>>> Great. I was planning to use linux-3.2, I hope the support is there ?
>>>
>>> It's been there for years, but some bit-rotting may have occurred.
>>
>> I'm assuming you have tried it on a FPGA solution, is that correct?
>
> It may have been a real silicon (core tile for a RealView EB board), I
> don't remember the details.
>

OK, I see.


>> We are planning to buy a Cortex-R4 board from ARM.
>> Lionel Belnet suggested to buy Versatile + a CoreTile with Cortex-R4F
>> r1p2 Test Chip on it.
>>
>> Is there any Linux/ucLinux support already offered for this solution?
>
> On www.arm.com/linux there is a uClinux tab with images for download,
> though the kernel is 2.6.35. Anyway, you can always get a newer kernel
> and just disable CONFIG_MMU for a RealView/EB board with ARMv6
> processor.
>

So, you are suggesting that we can got for a RealView + CoreTile with
Cortex-R4F testchip instead of versatile?

Why ARMv6?
Maybe you meant ARMv7?

Thx,
Arm


-- 
-- "Every step appears to be the unavoidable consequence of the
-- preceding one." (A. Einstein)
-- 
Armando Visconti                  Mobile: (+39) 346 8879146
Senior SW Engineer                Fax:    (+39) 02 93519290
CPG                               Work:   (+39) 02 93519683
Computer System Division          e-mail: armando.visconti at st.com
ST Microelectronics               TINA:   051  4683

Question on ARM Cortex R4 support in Linux

[Catalin Marinas]

On Mon, Feb 20, 2012 at 10:26:44AM +0000, Armando Visconti wrote:
> On 02/20/2012 11:01 AM, Catalin Marinas wrote:
> > On Mon, Feb 20, 2012 at 09:52:55AM +0000, Armando Visconti wrote:
> >> We are planning to buy a Cortex-R4 board from ARM.
> >> Lionel Belnet suggested to buy Versatile + a CoreTile with Cortex-R4F
> >> r1p2 Test Chip on it.
> >>
> >> Is there any Linux/ucLinux support already offered for this solution?
> >
> > On www.arm.com/linux there is a uClinux tab with images for download,
> > though the kernel is 2.6.35. Anyway, you can always get a newer kernel
> > and just disable CONFIG_MMU for a RealView/EB board with ARMv6
> > processor.
> 
> So, you are suggesting that we can got for a RealView + CoreTile with
> Cortex-R4F testchip instead of versatile?

I wasn't aware that we have a Versatile board supporting a Cortex-R4
tile. You could just mail support at arm.com and ask them to advise. I
recall I only tested with with a RealView/EB board.

> Why ARMv6?
> Maybe you meant ARMv7?

Yes, ARMv7 (ARM1156 is a v6).

-- 
Catalin

Question on ARM Cortex R4 support in Linux

[Catalin Marinas]

On 20 February 2012 10:26, Armando Visconti <armando.visconti@st.com> wrote:
> On 02/20/2012 11:01 AM, Catalin Marinas wrote:
>> On Mon, Feb 20, 2012 at 09:52:55AM +0000, Armando Visconti wrote:
>>>>>>> Has anybody used it on Cortex R4 based platform ?
>>>>>>
>>>>>> In theory Linux support for R4 should just work (once CONFIG_MMU is
>>>>>> disabled). I used to test it in the past regularly but not recently.
>>>>>
>>>>> Great. I was planning to use linux-3.2, I hope the support is there ?
>>>>
>>>> It's been there for years, but some bit-rotting may have occurred.
>>>
>>> I'm assuming you have tried it on a FPGA solution, is that correct?
>>
>> It may have been a real silicon (core tile for a RealView EB board), I
>> don't remember the details.
>>
>
> OK, I see.
>
>
>

>>> We are planning to buy a Cortex-R4 board from ARM.
>>> Lionel Belnet suggested to buy Versatile + a CoreTile with Cortex-R4F
>>> r1p2 Test Chip on it.
>>>
>>> Is there any Linux/ucLinux support already offered for this solution?
>>
>>
>> On www.arm.com/linux there is a uClinux tab with images for download,
>> though the kernel is 2.6.35. Anyway, you can always get a newer kernel
>> and just disable CONFIG_MMU for a RealView/EB board with ARMv6
>> processor.
>
> So, you are suggesting that we can got for a RealView + CoreTile with
> Cortex-R4F testchip instead of versatile?

I looked at the www.arm.com boards page and marketing now calls the
RealView EB (Emulation Baseboard) a Versatile board. I lost track of
the naming :). But yes, Versatile + R4 tile is the same as the one I
tested. In Linux just make sure that you configure it as RealView EB.

-- 
Catalin

Question on ARM Cortex R4 support in Linux

[Armando Visconti]

>>>> We are planning to buy a Cortex-R4 board from ARM.
>>>> Lionel Belnet suggested to buy Versatile + a CoreTile with Cortex-R4F
>>>> r1p2 Test Chip on it.
>>>>
>>>> Is there any Linux/ucLinux support already offered for this solution?
>>>
>>>
>>> On www.arm.com/linux there is a uClinux tab with images for download,
>>> though the kernel is 2.6.35. Anyway, you can always get a newer kernel
>>> and just disable CONFIG_MMU for a RealView/EB board with ARMv6
>>> processor.
>>
>> So, you are suggesting that we can got for a RealView + CoreTile with
>> Cortex-R4F testchip instead of versatile?
>
> I looked at the www.arm.com boards page and marketing now calls the
> RealView EB (Emulation Baseboard) a Versatile board. I lost track of
> the naming :). But yes, Versatile + R4 tile is the same as the one I
> tested. In Linux just make sure that you configure it as RealView EB.
>

Thx very much Catalin.

It is very clear and helpful from you!

Rgds,
Arm