[meta-freescale] [meta-fsl-arm][RFC][PATCH] image_types_fsl: Add extlinux support

[Otavio Salvador]

Hello Nikolay,

On Fri, Aug 28, 2015 at 7:35 PM, Nikolay Dimitrov <picmaster at mail.bg> wrote:
> Add support for booting via extlinux. This feature is supported only for U-Boot.
> Here is how it works - during boot U-Boot scans through a list of boot drives
> to find a partition containing the extlinux config file (this partition
> should be either marked as a bootable, or should be the 1st one of all the
> non-bootable partitions on the disk). The extlinux.conf file should be located
> on one of the following paths:
>
> /boot/extlinux/extlinux.conf
> /extlinux/extlinux.conf
>
> This patch uses the /extlinux/extlinux.conf path, in order to avoid funny paths
> (/boot/boot/...) if later the vfat bootable partition needs to be mounted
> (usually done at /boot).
>
> Here's an example extlinux.conf:
>
> default yocto
> label yocto
>         kernel /zImage
>         devicetree /imx6dl-riotboard.dtb
>         append console=ttymxc1,115200 root=/dev/mmcblk0p2 rw
>
> And this is an example machine.conf that can use extlinux boot mechanism:
>
> EXTLINUX_CONF = "yes"
> EXTLINUX_DEVICETREE = "imx6dl-riotboard.dtb"
> EXTLINUX_CONSOLE = "ttymxc1,115200"
> EXTLINUX_ROOTDEV = "/dev/mmcblk0p2 rw"
>
> Advantages:
> - Boot parameters are not hardcoded in the bootloader and can be managed by
>   userspace tools (including package managers)
> - One board can have multiple boot configurations
> - Others?
>
> Disadvantages:
> - My patch generates a simplified extlinux.conf with only 1 boot configuration.
>   Would be nice if we can have board-specific extlinux.conf, but I couldn't
>   find a proper way to do it
> - Boot params (devicetree, console) are duplicated because the extlinux/kernel
>   needs them in a format different from the existing in the machine.conf
> - Others?
>
> Signed-off-by: Nikolay Dimitrov <picmaster at mail.bg>

First I would like to thank you

-- 
Otavio Salvador                             O.S. Systems
http://www.ossystems.com.br        http://code.ossystems.com.br
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