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

[Nikolay Dimitrov]

Hi Otavio,

On 08/31/2015 10:28 PM, Otavio Salvador wrote:
> Hello Nikolay,
>
> (pressed too soon, Send)
>
> On Mon, Aug 31, 2015 at 1:27 PM, Otavio Salvador
> <otavio at ossystems.com.br> wrote:
>> 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
>
> ... for working on this.
>
> This is something we should really get moving and this is a very good base.
>
> However, I think we ought to reuse the syslinux class for this. Is it
> possible for you to take a look on this?

Sure, I'll look at it.

Regards,
Nikolay