Re: Adding aliases to mmc

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

On Sat, Sep 21, 2013 at 02:30:51PM +0200, Michael Olbrich wrote:
> Hi,
> 
> > > 
> > > An embedded system typically doesn't have an initrd. The kernel
> > > boots directly into the rootfs on SD/eMMC.
> > > 
> > > >>To my understanding, the UUID is different for each SD card/eMMC, correct?
> > > >
> > > >Yes by default.
> > > >
> > > >Although for an embedded product with a fixed eMMC, there's no reason
> > > >you couldn't make every device have the same UUID for the fixed device.
> > > 
> > > How do you make the eMMC on 1000 boards have the same UUID?
> > 
> > The same way you ensure an identical partition table in these 1000
> > boards. The disk signature is just a four byte value at offset 440 in
> > the MBR. Set this to your birthday or whatever on all boards, pass
> > root=PARTUUID=<yourbirthday>-01 on all boards and you're done.
> 
> Until someone inserts a SD-Card with the same disk signature...

Indeed. That would be a nice way to boot your own rootfs on otherwise
locked devices ;)

Sascha

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