Once Booted from MMC, eMMC not found

[Tim Kientzle]

> On Jul 3, 2015, at 12:00 PM, Tim Kientzle <tim at kientzle.com> wrote:
> 
> 
>> On Jul 2, 2015, at 9:46 PM, Glen Barber <gjb at FreeBSD.org> wrote:
>> 
>> Hi Tim,
>> 
>> On Thu, Jul 02, 2015 at 09:40:22PM -0700, Tim Kientzle wrote:
>>>> On Jul 2, 2015, at 7:35 AM, Glen Barber <gjb at FreeBSD.org> wrote:
>>>> 
>>>> I'm curious - is this even necessary to do anymore?
>>>> 
>>>> My latest tests (11-CURRENT and 10-STABLE) of BeagleBone Black images
>>>> "just boot."
>>>> 
>>>> Maybe I don't understand what this script is supposed to fix.  Can
>>>> someone clarify that for me?
>>> 
>>> The script just copies a running system booted from SD onto the eMMC so that a BBB can boot without an SD card.
>>> 
>>> The script just does the following:
>>> * Erases the eMMC
>>> * Reformats it
>>> * Copies boot files from SD to eMMC
>>> * Copies / from SD to eMMC (excluding a few things like /usr/src, /usr/obj that are unlikely to fit)
>>> * Tweaks a few configuration parameters on the copied system
>>> 
>> 
>> Ah, okay, this is the part I was missing.  I misunderstood what the eMMC
>> did overall, and wasn't sure how this interacted with the system in
>> whole.
> 
> The eMMC chip is connected to the second SD/MMC interface on the SoC.  To the kernel, it should look just like a second SD/MMC card on the second interface.
> 
> BBB can boot from eMMC to create a nice self-contained system.  At one time, Crochet’s BBB images could be easily copied to eMMC to boot from there without an SD card, but this doesn’t seem to work anymore due to changes in FreeBSD somewhere.
> 
> I stopped using the eMMC for booting myself simply because 2GB wasn’t enough for the things I was trying to do.  There are now BBB with 4G eMMC chips, so that may be worth looking into again.
> 

Is this bug still open?  If so, that would at least partly explain the problem.  FreeBSD’s newfs_msdos seems to still insist on omitting a partial final track from the total sector count and the AM335x boot ROM has always refused to boot from an MSDOS file system where the sector counts don’t match:

https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=183234 <https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=183234>

Tim