[Buildroot] [PATCH 1/1] Add default configuration for Raspberry Pi 2 (ARMv7 & NEON)

[Buildroot] [PATCH 1/1] Add default configuration for Raspberry Pi 2 (ARMv7 & NEON)

[James Hebden]

[Buildroot] [PATCH 1/1] Add default configuration for Raspberry Pi 2 (ARMv7 & NEON)

[Yann E. MORIN]

James, All,

On 2015-02-11 17:52 +1100, James Hebden spake thusly:
> From f73918e7f673845086503011d6130d4805e26549 Mon Sep 17 00:00:00 2001
> From: James Hebden <james@hebden.net.au>
> Date: Tue, 10 Feb 2015 08:51:50 +1100
> Subject: [PATCH 1/1] Added RPi2
> 
> I've put together a simple patch to add default a default config for
> the Raspberry Pi 2 Model B. Unlike earlier models the RPi2 supports
> ARMv7 instructions and NEON - so I've enabled those whilst compiling.
> It also sports a quad core processor so I've enabled SMP - those are
> the only substantial changes from the default configurations for the
> first edition Raspberry Pi. I've build and tested against a Raspberry
> Pi 2 model B booting from SD card and couldn't find any issues with the
> resulting image.
> 
> Signed-off-by: James Hebden <james@hebden.net.au>

Thank you for this patch.

However, here are a few comments:

  - your mailer wrapped long lines, so we can not apply it; please use
    "git-send-email" to send patches;

  - you provide a full Linux config file; this is huge and should be
    reduced to a defconfig. Use "make update-linux-defconfig" in your
    build directory to get a linux defconfig file;
    (B.B.: it's a pity they are not yet bundling a bcmrpi2_defconfig in
    the Linux kernel tree...)

  - you are doing two things in this patch: add a configuration for a
    new board, and bump the rpi-firmware version; this should be done in
    two different patches, the first to do the rpi-firmware version
    bump, the second to add the new board.


> +++ b/configs/raspberrypi_2_defconfig

I'd prefer the board be named raspberrypi2 (not raspberrypi_2).

> @@ -0,0 +1,21 @@
> +BR2_arm=y
> +BR2_cortex_a7=y
> +BR2_ARCH="arm"
> +BR2_ENDIAN="LITTLE"
> +BR2_GCC_TARGET_ABI="aapcs-linux"
> +BR2_GCC_TARGET_CPU="cortex-a7"
> +BR2_GCC_TARGET_FPU="neon-vfpv4"
> +BR2_GCC_TARGET_FLOAT_ABI="softfp"
> +BR2_GCC_TARGET_MODE="arm"
> +BR2_ARM_EABI=y

Don't we prefer EABIhf instead?

> +BR2_ARM_FPU_NEON_VFPV4=y

I've had a look on ARM's infocenter, and it is indeed a VFPv4-D32.

Note for my future-self: on Cortex-A7 (and A15):
  - VFPv4 without NEON is D16
  - VFPv4 with NEON is D32

http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.ddi0464f/BABDAHCE.html

> +BR2_TARGET_GENERIC_GETTY_PORT="tty1"
> +BR2_LINUX_KERNEL=y
> +BR2_LINUX_KERNEL_CUSTOM_GIT=y
> +BR2_LINUX_KERNEL_CUSTOM_REPO_URL="git://github.com/raspberrypi/linux.git"
> +BR2_LINUX_KERNEL_CUSTOM_REPO_VERSION="rpi-3.18.y-rebase"

We can not use a branch name here. We want either a tag or a sha1.
Currently, this is 0be82f722c097340632a59b879fbfee9c6148f53.

However, as the RPi folks often rebase tht branch, we can't guarantee
this sha1 will be available forever. There's nothing we can do about
this... :-(

Excep you may add a comment in this defconfig file.

> +BR2_LINUX_KERNEL_USE_CUSTOM_CONFIG=y
> +BR2_LINUX_KERNEL_CUSTOM_CONFIG_FILE="board/raspberrypi/linux-3.18-rpi-2.defconfig"
> +BR2_LINUX_KERNEL_ZIMAGE=y
> +BR2_PACKAGE_RPI_FIRMWARE=y
> +BR2_PACKAGE_RPI_FIRMWARE_INSTALL_DTBS=y
> diff --git a/package/rpi-firmware/rpi-firmware.mk
> b/package/rpi-firmware/rpi-firmware.mk index 03178d5..c7c668c 100644
> --- a/package/rpi-firmware/rpi-firmware.mk
> +++ b/package/rpi-firmware/rpi-firmware.mk
> @@ -4,7 +4,7 @@
>  #
>  ################################################################################
>  
> -RPI_FIRMWARE_VERSION = 393dcc0e76f18f6ac1b67ba45d36058410670034
> +RPI_FIRMWARE_VERSION = d10602a5f3f3788ed673d98e3dec2af25666365d
>  RPI_FIRMWARE_SITE = $(call
> github,raspberrypi,firmware,$(RPI_FIRMWARE_VERSION))
> RPI_FIRMWARE_LICENSE = BSD-3c RPI_FIRMWARE_LICENSE_FILES =
> boot/LICENCE.broadcom

See hos the long lines get mangled above? Using git-send-email would not
exhibit this problem.

Care to address the issues and resubmit, please?

Thank you! :-)

Regards,
Yann E. MORIN.

-- 
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|  Yann E. MORIN  | Real-Time Embedded | /"\ ASCII RIBBON | Erics' conspiracy: |
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[Buildroot] [PATCH 1/1] Add default configuration for Raspberry Pi 2 (ARMv7 & NEON)

[Floris Bos]

Hi,

On 02/12/2015 08:09 PM, Yann E. MORIN wrote:
> James, All,
>
> On 2015-02-11 17:52 +1100, James Hebden spake thusly:
>>  From f73918e7f673845086503011d6130d4805e26549 Mon Sep 17 00:00:00 2001
>> From: James Hebden <james@hebden.net.au>
>> Date: Tue, 10 Feb 2015 08:51:50 +1100
>> Subject: [PATCH 1/1] Added RPi2
>>
>> I've put together a simple patch to add default a default config for
>> the Raspberry Pi 2 Model B. Unlike earlier models the RPi2 supports
>> ARMv7 instructions and NEON - so I've enabled those whilst compiling.
>> It also sports a quad core processor so I've enabled SMP - those are
>> the only substantial changes from the default configurations for the
>> first edition Raspberry Pi. I've build and tested against a Raspberry
>> Pi 2 model B booting from SD card and couldn't find any issues with the
>> resulting image.
>>
>> Signed-off-by: James Hebden <james@hebden.net.au>
> Thank you for this patch.
>
> However, here are a few comments:
>
>    - your mailer wrapped long lines, so we can not apply it; please use
>      "git-send-email" to send patches;
>
>    - you provide a full Linux config file; this is huge and should be
>      reduced to a defconfig. Use "make update-linux-defconfig" in your
>      build directory to get a linux defconfig file;
>      (B.B.: it's a pity they are not yet bundling a bcmrpi2_defconfig in
>      the Linux kernel tree...)

The Linux defconfig for the Pi 2 is called bcm2709_defconfig


Yours sincerely,

Floris Bos

[Buildroot] [PATCH 1/1] Add default configuration for Raspberry Pi 2 (ARMv7 & NEON)

[Yann E. MORIN]

Floris, James, All,

On 2015-02-12 20:56 +0100, Floris Bos spake thusly:
> On 02/12/2015 08:09 PM, Yann E. MORIN wrote:
[--SNIP--]
> >     (B.B.: it's a pity they are not yet bundling a bcmrpi2_defconfig in
> >     the Linux kernel tree...)
> 
> The Linux defconfig for the Pi 2 is called bcm2709_defconfig

Ah, nice. Thanks for the hint! :-)

James, since there is a defconfig in the Linux kernel, we prefer to use
it rather than bundle a custom defconfig.

Thanks!

Regards,
Yann E. MORIN.


-- 
.-----------------.--------------------.------------------.--------------------.
|  Yann E. MORIN  | Real-Time Embedded | /"\ ASCII RIBBON | Erics' conspiracy: |
| +33 662 376 056 | Software  Designer | \ / CAMPAIGN     |  ___               |
| +33 223 225 172 `------------.-------:  X  AGAINST      |  \e/  There is no  |
| http://ymorin.is-a-geek.org/ | _/*\_ | / \ HTML MAIL    |   v   conspiracy.  |
'------------------------------^-------^------------------^--------------------'

[Buildroot] [PATCH 1/1] Add default configuration for Raspberry Pi 2 (ARMv7 & NEON)

[Frank Hunleth]

Yann and James,

>> +BR2_LINUX_KERNEL_CUSTOM_REPO_VERSION="rpi-3.18.y-rebase"
>
> We can not use a branch name here. We want either a tag or a sha1.
> Currently, this is 0be82f722c097340632a59b879fbfee9c6148f53.

Regarding the Raspberry Pi kernel version, what's the difference
between using the tip of the rpi-3.18.y branch and the tip of the
rpi-3.18.y-rebase branch? The kernel source code looks the same
between branches except for some trailing whitespace in files. Is the
rpi-3.18.y branch safe from rebases?

Frank

[Buildroot] [PATCH 1/1] Add default configuration for Raspberry Pi 2 (ARMv7 & NEON)

[Yann E. MORIN]

Frank, All,

On 2015-02-12 15:51 -0500, Frank Hunleth spake thusly:
> >> +BR2_LINUX_KERNEL_CUSTOM_REPO_VERSION="rpi-3.18.y-rebase"
> >
> > We can not use a branch name here. We want either a tag or a sha1.
> > Currently, this is 0be82f722c097340632a59b879fbfee9c6148f53.
> 
> Regarding the Raspberry Pi kernel version, what's the difference
> between using the tip of the rpi-3.18.y branch and the tip of the
> rpi-3.18.y-rebase branch? The kernel source code looks the same
> between branches except for some trailing whitespace in files. Is the
> rpi-3.18.y branch safe from rebases?

No, the rpi-3.18.y is *not* safe from rebase; in fact, it is "constantly"
rebased. That's a shame. :-(

As for the rpi-3.18.y-rebase branch, I have absolutely no idea what it
is meant for:
  - is it a temporary branch that got pushed (it did not exist until a
    few days ago)?
  - is it the branch that will be rebased, leaving rpi-3.18.y alone?
  - something else?

So, I would prefer we stick to using the rpi-3.18.y (or even the
rpi-3.19.y) branch, since we pretty much know how they handle it.

/me should probably go and bug the RPi guys to put some tags on their
    branches from time to time...

Regards,
Yann E. MORIN.

-- 
.-----------------.--------------------.------------------.--------------------.
|  Yann E. MORIN  | Real-Time Embedded | /"\ ASCII RIBBON | Erics' conspiracy: |
| +33 662 376 056 | Software  Designer | \ / CAMPAIGN     |  ___               |
| +33 223 225 172 `------------.-------:  X  AGAINST      |  \e/  There is no  |
| http://ymorin.is-a-geek.org/ | _/*\_ | / \ HTML MAIL    |   v   conspiracy.  |
'------------------------------^-------^------------------^--------------------'

[Buildroot] [PATCH 1/1] Add default configuration for Raspberry Pi 2 (ARMv7 & NEON)

[James Hebden]

On 13/02/15 08:03, Yann E. MORIN wrote:
> Frank, All,
>
> On 2015-02-12 15:51 -0500, Frank Hunleth spake thusly:
>>>> +BR2_LINUX_KERNEL_CUSTOM_REPO_VERSION="rpi-3.18.y-rebase"
>>>
>>> We can not use a branch name here. We want either a tag or a sha1.
>>> Currently, this is 0be82f722c097340632a59b879fbfee9c6148f53.
>>
>> Regarding the Raspberry Pi kernel version, what's the difference
>> between using the tip of the rpi-3.18.y branch and the tip of the
>> rpi-3.18.y-rebase branch? The kernel source code looks the same
>> between branches except for some trailing whitespace in files. Is the
>> rpi-3.18.y branch safe from rebases?
>
> No, the rpi-3.18.y is *not* safe from rebase; in fact, it is "constantly"
> rebased. That's a shame. :-(
>
> As for the rpi-3.18.y-rebase branch, I have absolutely no idea what it
> is meant for:
>    - is it a temporary branch that got pushed (it did not exist until a
>      few days ago)?
>    - is it the branch that will be rebased, leaving rpi-3.18.y alone?
>    - something else?
>
> So, I would prefer we stick to using the rpi-3.18.y (or even the
> rpi-3.19.y) branch, since we pretty much know how they handle it.
>
> /me should probably go and bug the RPi guys to put some tags on their
>      branches from time to time...
>
> Regards,
> Yann E. MORIN.
>

Thanks everyone for reviewing the patch and all of your helpful advice - 
much appreciated.

I'll resubmit the patch shortly, I'm just testing an image compiled with 
everyone's suggestions.

I've
  * Removed the custom kernel config, I'm now using bcm2709_defconfig.
  * Switched to the current tip of the rpi-2.19.y branch, using the 
commit ref instead of branch name. At the time I composed the patch I 
recall the rpi-3.18.y-rebase branch having a few more RPi2 related 
fixes, hence the choice. They seem identical now.
  * Cut down the size of the buildroot defconfig I've created. It's a 
proper defconfig now.
  * Switched to EABIhf. I recall testing this and not being able to get 
the image to boot, and meaning to switch it back on once I got the image 
booting. Good catch :)
  * Removed the rpi-firmware version change - I'll also be submitting a 
separate patch to bump the rpi-firmware package to the required level.

Sorry about the patch formatting - I had tried git send-email maybe a 
dozen times before resorting to using my mail reader to send the patch. 
Didn't noticed the wrapped lines until now - so I'll give git send-email 
another try.

Thanks,
James

[Buildroot] [PATCH 1/1] Add default configuration for Raspberry Pi 2 (ARMv7 & NEON)

[James Hebden]