Hello,

May I ask for a update on these plans?

On Mon, 2014-04-21 at 09:29 +0200, John Crispin wrote:
> 
> On 21/04/2014 07:06, Ben Mulvihill wrote:
> > Hi John,
> > 
> > May I take up your offer of a hand with overlayfs on top of ubi? I
> > have in fact managed to get a working overlay + ubi image, and also
> > a ubifs image. But I still have a few questions:
> > 
> > - Am I right in thinking that there is no way to concatenate the 
> > kernel and ubi image and have them split automatically like with 
> > the squashfs image without ubi?
> 
> i added a ubi-flash tool to trunk that can be used to flash ubi
> volumes (and implicitly resize them)
> 
> i plan to add a wrapper script this week. this script will be fed a
> tar file with the kernel and rootfs image. this allows us to "split"
> the files when flashing.

Any progress on this? I can't find it, but maybe I am looking in the
wrong place.

> 
> i am using fixed size kernel part sizes for nand, there is enough
> space anyhow.
> 
> 
> > - the two images require different kernel parameters in the
> > 'chosen' line of the device tree: ubi.mtd=rootfs_ubi,256
> > root=/dev/mtdblock8 // for overlayfs ubi.mtd=rootfs_ubi,256
> > root=ubi0:rootfs    // for ubifs Is there any way of combining them
> > so that a single device tree can be used with both images? Passing
> > the parameters from uboot ought to be one way of dealing with the
> > problem but I believe that with recent kernels parameters passed in
> > that way just get clobbered.
> 
> i have a patch in my queue that will make the kernel auto-attach the
> rootfs_ubi mtd making the volumes inside it mountable. i will do my
> best to finsih the patch before the week is over. this will spare us
> the cmdline clobbering and not depend on any uboot environemnt variables.
> 

I see that this patch has been merged. Now I no longer need to specify
root=/dev/mtdblock8 on the command line when using overlayfs
on top of ubi. But I still need root=ubi0:rootfs when using ubifs.
So the same device tree still cannot be used to generate both images.
Is this right, or am I doing something wrong?

> 
> > - What is the best way to get the get the image onto the target? 
> > nand write from uboot works fine, but you lose the wear levelling 
> > information each time. I have also use tried booting a ramdisk 
> > image first, copying root-overlay.ubi to /tmp, and flashing it with
> > ubiformat -f. That works too, but is there another option?
> 
> on first flash you need to run ubi-format once. my plan is to push a
> special initramfs that has the ubi tools inside and carries the target
> rootfs as a payload. you flash/boot that image and it will do the rest
> of the firstboot/ubi-format for you. this will be part of the wrapper
> script mentioned above
> 

Not ready yet I assume?

Many thanks,

Ben
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