[PATCH/RFC 0/3] UBI: unify mouting rootfs based on cmdline parameter

[Ezequiel Garcia]

On 28 August 2016 at 11:20, Boris Brezillon
<boris.brezillon at free-electrons.com> wrote:
> On Sun, 28 Aug 2016 11:12:50 -0300
> Ezequiel Garcia <ezequiel at vanguardiasur.com.ar> wrote:
>
>> Daniel,
>>
>> Let's try to tackle this from a different angle.
>>
>> On 27 August 2016 at 16:43, Daniel Golle <daniel at makrotopia.org> wrote:
>> > Hi!
>> >
>> > In an attempts to fix the flaws of the current set of UBI-related
>> > patches we are carrying in OpenWrt, I re-wrote the way mounting the
>> > rootfs from UBI in OpenWrt/LEDE works. The main requirement I face
>> > which cannot be easily addressed using other means which are already
>> > available in the kernel is the fact that UBIFS and squashfs-on-UBI
>> > require different parameters to be set on the cmdline, e.g.
>> > for UBIFS: ubi.mtd=ubi root=ubi0:rootfs rootfstype=ubifs
>> > for squashfs: ubi.mtd=ubi ubiblock=0,1 root=/dev/ubiblock0_1 rootfstype=squashfs
>> >
>>
>> Can you help me understand the problem you are solving here?
>>
>> So you currently need to do:
>>
>> * for UBIFS: ubi.mtd=ubi root=ubi0:rootfs rootfstype=ubifs
>> * for squashfs: ubi.mtd=ubi ubi.block=0,1 root=/dev/ubiblock0_1
>> rootfstype=squashfs
>>
>> [..]
>> >
>> > With those changes, a single set of cmdline parameters is
>> > sufficient to mount either UBIFS or any other block filesystem
>> > by creating a ubiblock device:
>> > ubi.mtd=ubi root=ubi0:rootfs rootfstype=ubifs,squashfs
>> >
>>
>> And you would like to do:
>>
>> * for UBIFS: ubi.mtd=ubi root=ubi0:rootfs rootfstype=ubifs
>> * for squashfs: ubi.mtd=ubi root=/dev/ubiblock0_1 rootfstype=squashfs
>
> I think Daniel wants something like:
>
> ubi.mtd=1 root=ubi0:rootfs
>
> or
>
> ubi.mtd=1 root=/dev/ubiblock0_1
>
> to work for both the UBIFS and squashfs cases.
>

Right. In which case, I was going to propose the same thing
you just did! It would be simple, and uninvasive to introduce
something like the parameter you suggested
"ubi.block=attach_all_ro_vols".

After all, this is what mtdblock does, so it wouldn't be
a too revolutionary approach.
-- 
Ezequiel García, VanguardiaSur
www.vanguardiasur.com.ar