On Mon, 26 Feb 2018 23:29:49 +0300
"Matwey V. Kornilov" <[email protected]> wrote:

> 2018-02-26 23:18 GMT+03:00 Alexander Graf <[email protected]>:
> >
> >
> > On 26.02.18 20:36, Matwey V. Kornilov wrote:  
> >> 2018-02-26 22:07 GMT+03:00 Alexander Graf <[email protected]>:  
> >>>
> >>>
> >>> On 26.02.18 08:19, Matwey V. Kornilov wrote:  
> >>>> 2018-02-26 0:06 GMT+03:00 Alexander Graf <[email protected]>:  
> >>>>>
> >>>>>  
> >>>>>> Am 25.02.2018 um 16:37 schrieb Matwey V. Kornilov
> >>>>>> <[email protected]>:
> >>>>>>
> >>>>>> 25.02.2018 18:22, Matwey V. Kornilov пишет:  
> >>>>>>>
> >>>>>>> Hi,
> >>>>>>>
> >>>>>>> I am faced the issue that recent JeOS builds cannot be read
> >>>>>>> by u-boot:
> >>>>>>>
> >>>>>>> ls mmc 1:2 /
> >>>>>>> Failed to mount ext2 filesystem...
> >>>>>>> ** Unrecognized filesystem type **  
> >>>>>>
> >>>>>> Hm, Now I see. Why do you use btrfs for having separate /boot
> >>>>>> partition? Is there any reason for it?  
> >>>>>
> >>>>> I assume that change came with the seitch to python-kiwi. I
> >>>>> assume the main rationale would be snapshotting of /boot, so
> >>>>> you can load old kernels. 
> >>>>
> >>>> /lib/modules are on the separate partition, so it won't work
> >>>> anyway. We could have united / and put dtb files onto separate
> >>>> EFI partition for snapshotting kernels.  
> >>>
> >>> Nah, if you go that far, better ensure the built-in device tree
> >>> from U-Boot contains a device tree that just covers everything
> >>> you need. That way you don't need to load any dtb files. The dtb
> >>> loading from /boot is really mostly there for cases where
> >>> firmware is "broken" and does not deliver good, upstream
> >>> compatible device trees. 
> >>
> >> Well, it would be full of pain way, especially in cases when one
> >> bootloader fits multiple dtb-s (i.e. am335x).  
> >
> > It depends. Currently, U-Boot needs to detect the board and find a
> > different dtb. Instead, it could easily just pick a different
> > built-in dtb.
> >
> > Depending on the board you're on, it may even be the easiest way
> > forward. As soon as U-Boot 2018.03 is in Factory, I'll move the
> > Raspberry Pi to a model where the RPi firmware provided devices tree
> > gets propagated all the way to U-Boot as well as Linux. And that
> > makes things easier at the end of the day, because we don't need to
> > synchronize 3 different DTs throughout the boot process.
> >  
> 
> At least, neither rk3328 nor marvel 3700 espressobin not able to boot
> the kernel using bundled u-boot dtb.
> I think this should be primarily solved upstream, if they would manage
> to merge dts trees between different projects.
> 

I think the goal is to support the features required by u-boot by the
DT included in u-boot and new development happens in Linux with
occasional sync. As in it is not expected that the tree provided by
u-boot will work with Linux as well without extra effort.

So there are a few options here:

 - update devicetrees for boards we build for in u-boot. This might not
   work flawlessly due to driver differences between u-boot and Linux.
   This should not happen but some bugs might creep in occasionally
 - provide separate package of devicetrees which is completely separate
   from kernel and u-boot and installs devicetrees somewhere where the
   u-boot scripts find them
 - update, build and use the devicetrees from Linux - some dtb packages
   are built but the devicetrees are not updated on the basis that the
   in-kernel devicetrees are not used for booting ?????

Thanks

Michal
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