[meta-freescale] Kernel 3.10.31 and SD card numbering and boot scripts

[Otavio Salvador]

On Thu, Oct 9, 2014 at 9:00 PM, Eric Nelson
<eric.nelson at boundarydevices.com> wrote:
> The 3.10.31 kernel contains a nifty bit of code from Sascha Hauer
> that addresses the question of SD card numbering (device naming)
> quite well:
>
>         http://git.freescale.com/git/cgit.cgi/imx/linux-2.6-imx.git/commit/drivers/mmc/card/block.c?h=imx_3.10.31_1.1.0_beta&id=5f9447e5d97060207c4742d5a06e5548de45972d
>         https://www.mail-archive.com/linux-mmc@vger.kernel.org/msg26472.html
>
> Unfortunately, it also changes the requirements for the kernel
> command-line and breaks our boot scripts.

Yes.

> This is probably a good time to ask a related question about
> where we're keeping boot scripts.
>
> We have been compiling boot scripts out of our U-Boot tree
> from a Yocto-specific "6x_bootscript-yocto.txt" that implements
> the conventions of the Freescale Community BSP (kernel in
> the root of partition 1 and rootfs in partition 2).
>
> Since boot scripts have dependencies on a lot of things, it's
> not clear to me that they belong in the U-Boot source tree
> and that a Yocto-specific boot script really belongs directly
> in the Yocto tree somewhere.
>
> Since a Yocto build knows about the PREFERRED_VERSION of the
> kernel, it would be straightforward to have multiple versions
> of a boot script.
>
> Otherwise, we'd need to place a couple of versions in the
> U-Boot tree:
>         6x_bootscript-yocto.txt
>         6x_bootscript-yocto-after-3.10.17.txt
> and we'd also need some logic in u-boot-script-boundary.bb
> to choose between them.
>
> Before crafting a patch to do this, I'd like to get some feedback.

It is harder than it seems to be. The providing system does not track
versions so you'd need to do some "uglyness" to make this work.

Personally I think it is easier to address this on the bootscript
itself using the setexpr command in U-Boot and with the REGEX config
enabled. So you could try to match the kernel version on it somehow.

Not sure if we have a command to 'ask' for the kernel version loaded though...

-- 
Otavio Salvador                             O.S. Systems
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