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

[Otavio Salvador]

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?

-- 
Otavio Salvador                             O.S. Systems
http://www.ossystems.com.br        http://code.ossystems.com.br
Mobile: +55 (53) 9981-7854            Mobile: +1 (347) 903-9750