Re: does beaglebone black device tree need to specify amount of eMMC flash?

[Alexander Aring <alex.aring@gmail.com>]

On Mon, Jul 07, 2014 at 08:53:45AM +0200, Sascha Hauer wrote:
> On Sat, Jul 05, 2014 at 06:47:36AM -0400, Robert P. J. Day wrote:
> > 
> >   (aside: i'm digging into device trees in barebox and will certainly
> > have a number of questions shortly so i can write some tutorials for
> > an upcoming class, but i'll start simple.)
> > 
> >   i'm particularly interested in configuring and building barebox for
> > my beaglebone black (henceforth "BBB"), and i can see all of the .dts*
> > support files under arch/arm/dts/, but a simple question -- the *new*
> > BBB has upgraded from 2G of eMMC to 4G eMMC, but i don't see that
> > mentioned anywhere in those .dts files. does that property need to be
> > mentioned, or is that simply autodetected by the kernel at boot time?
> 
> eMMC size is autodetected by barebox and the kernel. In the end it's
> just a MMC/SD card.
> 

btw.: that's why eMMC is evil.

Raw-Flash:

Disadvantage:
 - you can't replace it.

Advantage:
 - no mcu in the middle, access the raw Flash.


- MMC/SD:

Disadvantage:
 - mcu in the middle, abstract block device. OS doesn't know about this.

Advantage:
 - you can replace it.


Combines these Disadvantage and Advantage you will get:

Disadvantage:
 - mcu in the middle, abstract block device. OS doesn't know about this.
 - you can't replace it.

Advantage:
 - maybe a little bit cheaper...
 - maybe avoid some bad connections (never expired by using sd cards)

For the marketing you can say if your eMMC is broken, then buy a new
complete board. This kind of marketing is very bad. :-(

- Alex

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