[Buildroot] [PATCH v4] board: add support for Synopsys VDK Software Development Platform

[Yann E. MORIN <yann.morin.1998@free.fr>]

Joao, All,

On 2015-10-12 10:34 +0100, Joao Pinto spake thusly:
> The Virtualizer Development Kit (VDK) Family for ARM Cortex Products
> consists of a set of virtual prototypes that provide a virtualizer for 
> the ARM core variants. The VDK is a standalone package that runs on an 
> host computer.
> 
> Remark: 'Image' boot argument was removed.

That last line does not belong to the commit log. I nstead, it should be
part of the 'changelog' of the patch.

Such a changelog is written after a three-dash line, like so:

    title: brief explanation of the patch

    Body of the commitlog, with more
    in-depth explanations of what it
    is doing.

    Signed-off-by: Your Real Name <your-emain@address>

    ---
    Changes v3 -> v4:
      - drop 'Image' boot option (Thomas)

    Changes v2 -> v3:
      - "some thing changed" (Someone)

    and so on...

This way, when a maintainer applies your patch, only what is above the
three-dash line is kept in the git tree. Whatever is after the
three-dash line gets removed.

The changlog (after the ---) is there to help reviewers see how the
patch has evolved, and adapt their reviews accordingly, with the first
name of the reviewer between ().

> Signed-off-by: Joao Pinto <jpinto@synopsys.com>
> ---
>  board/synopsys/vdk/linux-vdk-aarch64-defconfig | 226 +++++++++++++++++++++++++
>  configs/snps_aarch64_vdk_defconfig             |  15 ++
>  2 files changed, 241 insertions(+)
>  create mode 100644 board/synopsys/vdk/linux-vdk-aarch64-defconfig
>  create mode 100644 configs/snps_aarch64_vdk_defconfig
> 
> diff --git a/board/synopsys/vdk/linux-vdk-aarch64-defconfig b/board/synopsys/vdk/linux-vdk-aarch64-defconfig
> new file mode 100644
> index 0000000..f90f2ca
> --- /dev/null
> +++ b/board/synopsys/vdk/linux-vdk-aarch64-defconfig
> @@ -0,0 +1,226 @@
> +CONFIG_SYSVIPC=y
> +CONFIG_POSIX_MQUEUE=y
> +CONFIG_NO_HZ=y
> +CONFIG_HIGH_RES_TIMERS=y
> +CONFIG_BSD_PROCESS_ACCT=y

This is not a minimal defconfig. I doubt BSD process acounting is
required to have Linux run successfully on the VDK,  is it?

Similarly, options that are not strictly required should not be enabled.
For example, having netfilter enabled is probably not needed either.
Same goes for a lot of the other options.

We are trying to get the minimalist kernel option that just makes the
board boot, with the meaningfull driver to suport the hardware
(ethernet, WiFi, MMC, whatever HW is present...) but not much more.

Having IPv4 (maybe v6) is meaningfull, but having bridge, netfilter or
ebtables, TUN, SCSI, MD and so on is probably not. Also, if you're using
virtio-net to do networking, then an ethernet driver is probably not
required...

Similarly, if the rootfs is ext2, then you don;t need the other
filesystems. Maybe you can disable ext2 and ext3 support, enable ext4
and use it for ext2/3 (CONFIG_EXT4_USE_FOR_EXT2).

9p and 9p-virtio are probably not required either, but having them for
virtio-mounting from the host kinda makes sense...

I know you've already done a few rounds on that patch, but could you
'cleanup' that defconfig as I explained above?

[--SNIP--]
> diff --git a/configs/snps_aarch64_vdk_defconfig b/configs/snps_aarch64_vdk_defconfig
> new file mode 100644
> index 0000000..a79b1d2
> --- /dev/null
> +++ b/configs/snps_aarch64_vdk_defconfig
> @@ -0,0 +1,14 @@
> +BR2_aarch64=y
> +BR2_KERNEL_HEADERS_3_18=y
> +BR2_TARGET_GENERIC_HOSTNAME="vdk-buildroot"
> +BR2_TARGET_GENERIC_ISSUE="Welcome to SNPS VDK by Buildroot"
> +BR2_LINUX_KERNEL=y
> +BR2_LINUX_KERNEL_CUSTOM_GIT=y
> +BR2_LINUX_KERNEL_CUSTOM_REPO_URL="https://git.linaro.org/kernel/linux-linaro-tracking.git"
> +BR2_LINUX_KERNEL_CUSTOM_REPO_VERSION="linux-linaro-3.18-2014.12"
> +BR2_LINUX_KERNEL_USE_CUSTOM_CONFIG=y
> +BR2_LINUX_KERNEL_CUSTOM_CONFIG_FILE="board/synopsys/vdk/linux-vdk-aarch64-defconfig"
> +BR2_LINUX_KERNEL_IMAGE_TARGET_CUSTOM=y
> +BR2_LINUX_KERNEL_IMAGE_TARGET_NAME="Image"
> +BR2_TARGET_ROOTFS_EXT2=y
> +# BR2_TARGET_ROOTFS_TAR is not set

Otherwise, this defconfig looks OK! :-)

Regards,
Yann E. MORIN.

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