Re: [RFC PATCH 0/4] Introduce global.bootm.root env var for booting via PARTUUID

[Sascha Hauer <s.hauer@pengutronix.de>]

On Mon, Jul 13, 2020 at 01:18:04PM +0200, Robert Karszniewicz wrote:
> On 7/9/20 4:14 PM, Sascha Hauer wrote:
> > On Tue, Jun 30, 2020 at 03:48:30PM +0200, Robert Karszniewicz wrote:
> > > This patch introduces a new env var which specifies which device
> > > is the rootfs device to be used in Linux, passed to Linux via bootargs,
> > > identified by the rootfs partition's PARTUUID.
> > > 
> > > global.bootm.root supplements global.bootm.appendroot, in that it overrides
> > > appendroot's naïve default, which picks the partition that the kernel resides
> > > on (global.bootm.image).
> > > 
> > > I don't know if it is the right way, or a good way, but this is the shortest
> > > and simplest way that I've found.
> > > 
> > > What do you think of this? And is it generally something that would be
> > > accepted, or is this out of scope for barebox?
> > > 
> > > Example:
> > > detect mmc2
> > > global.bootm.image='/mnt/mmc2.0/zImage'
> > > global.bootm.appendroot=1
> > > global.bootm.root='/mnt/mmc2.1/'
> > 
> 
> Generally, this was just the shortest possible way to make it basically
> work, before I knew if such a feature would be accepted at all.
> 
> > Why do you pass the standard mount path here? I would expect /dev/mmc2.1.
> > 
> 
> Agree.
> 
> > In 4/4 you mount the root device. I think this should be avoided as it
> 
> Agree.
> 
> > only works when barebox has support for the rootfs, i.e. it doesn't work
> > for XFS or the like.
> > 
> 
> I see.
> 
> > Ok, fsdev_set_linux_rootarg() is tied to a filesystem, so maybe we need
> > something similar for a cdev.
> > 
> > Generally I think barebox should support this usecase, but I am not
> > convinced the approach you took is the right API.
> > 
> 
> So do I understand it correctly, that doing it via a new 'root_dev' variable
> is fine, just that the implementation needs to be better?

Yes.

Sascha

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