Re: /dev/disk0 vs /dev/mmc0

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

On Mon, Oct 07, 2013 at 08:32:03AM +0200, David Jander wrote:
> 
> Dear Sascha,
> 
> On Sun, 6 Oct 2013 12:39:50 +0200
> Sascha Hauer <s.hauer@pengutronix.de> wrote:
> > 
> > It doesn't interfere with the kernel. The kernel currently ignores this
> > aliases. There are patches floating to let the kernel honor this
> > aliases, but then they should simply have the same effect as they have
> > in barebox.
> 
> That doesn't _feel_ right. Changing standard device names in Linux via aliases
> in the DT might be a fancy idea, but it'd have a different reason/use-case
> than in the case of barebox. IMHO using the same DT for both seems to be the
> Right Thing (tm) to do, but then the semantics must be the same also.
> If I need aliases in the DT only to be able to tell devices apart from each
> other in barebox, while in Linux the effect would only be a rather inconvenient
> renaming of devices with no other added value, I think we need a different way
> to differentiate devices in barebox. Why not just use a simple driver-provided
> prefix (mci, mmc, usb, sata, etc...) for now?

That's not enough. We also need a fixed numbering. Otherwise a
nonremovable eMMC and a removable SD card change their device names
depending on the detect order.

Using aliases to provide a numbering is done in the Kernel aswell at
least for gpios, uarts and i2c busses, so expanding this scheme to
mmc/sd slots doesn't feel too wrong to me.

Sascha

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