Re: Adding aliases to mmc

On Sat, Sep 21, 2013 at 02:30:51PM +0200, Michael Olbrich wrote:

Hi,

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An embedded system typically doesn't have an initrd. The kernel
boots directly into the rootfs on SD/eMMC.

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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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