Support for MTD devices (NAND/NOR Flash)

Mark Shuttleworth mark at
Mon Feb 29 19:02:24 UTC 2016

In principle, that should all be workable. Our thinking is that the
gadget snap would specify the update mechanisms for the NOR flash in
your scheme, and the NAND flash would be the UBI FS as you describe.


On 29/02/16 13:47, Wolfgang Tolkien wrote:
> Would there be any issues regarding the kernel? On MTD devices, the
> kernel typically resides in a separate partition with no underlying
> file system at all. The same applies to the bootloader partition,
> which also has no file system. Would this cause any major
> complications with the existing snappy architecture?
> To be more specific, I currently have an AP148 development in front of
> me, which has a Qualcomm IPQ8064 CPU (2x 1.4 GHz ARM) with 32MB NOR
> flash and 256MB NAND flash (which could eventually be increased). The
> CPU boots off the NOR flash, which contains a number of Qualcomm
> specific bootloaders and eventually passes control over to u-boot.
> U-boot then loads the kernel. Each of these components (various
> bootloaders and kernel) reside in their own partition on NOR flash.
> The kernel eventually loads a UBI root file system from NAND flash.
> So there might be a little bit more to it then just replacing ext4
> with ubifs. And before we start any work on this, I'd like to find out
> if this architecture would pose any fundamental problems.
> Wolfgang
> On 16-02-29 03:57 AM, Mark Shuttleworth wrote:
>> In principle, any read-write filesystem is fine for the bulk partition
>> of snaps and user data. We understand the value of wear-levelling
>> filesystems and would be glad to see those integrated. There may be some
>> constraints imposed by firmware, but if your device supports it we can
>> get there.
>> There may be work to be done (over time we expect to flesh out support
>> for more complex cases, such as NVRAM storage of critical items) but it
>> all seems achievable on the 16.04 branch (which will continue to evolve
>> even though the actual OS is stable).
>> Mark
>> On 29/02/16 06:03, Wolfgang Tolkien wrote:
>>> I'm new to Snappy, and so far it seems very impressive! I have a few
>>> questions though: we are looking at Snappy as a possible platform for
>>> future products and I noticed that all the hardware platforms that are
>>> supported so far seem to have SD/MMC/eMMC storage (or of course
>>> regular HDDs/SSDs for larger systems)
>>> Is it possible to run Snappy on hardware that uses MTD devices in
>>> combination with filesystems such as UBI or JFFS2?
>>> And if the answer is no, are there any plans to support this in the
>>> future?
>>> Many thanks,
>>> Wolfgang

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