I maybe having a similar issue. I have BBB Rev C. It had been running fine for 20+ months. Feeling that it was a bit dated I ran a 'pacman -Syu' to get it current last weekend. After the update the boot hung reporting "Waiting for root device /dev/mmcblk0p2".
I then went to
https://archlinuxarm.org/platforms/armv ... bone-black and reinstalled on a SD cards after clearing the onboard eMMC with a 'mmc erase ...' Now the board refuses to boot from the SD card.
I believe the issue to be in the with the "bootcmd" script but I haven't figured it out yet. I thought the install directions seems wrong, there used to be two partitions, one FAT-32 and the other ext4. Has that been removed? The "bootcmd" executes "setenv bootpart 1:2" before executing "run mmcboot" but there's only one partition on the SD card falling the current installation instructions.
Here's the partitions on the mmc devices:
U-Boot# mmc dev 0
switch to partitions #0, OK
mmc0 is current device
U-Boot# mmc part
Partition Map for MMC device 0 -- Partition Type: DOS
Part.Start Sector.Num Sectors.UUID..Type
1.2048 .15521792 .187fded0-01.83
U-Boot# mmc dev 1
switch to partitions #0, OK
mmc1(part 0) is current device
U-Boot# mmc part
## Unknown partition table
U-Boot#
Now I see the following on the serial port.
U-Boot 2015.04 (Jun 07 2015 - 19:26:11)
Watchdog enabled
I2C: ready
DRAM: 512 MiB
MMC: OMAP SD/MMC: 0, OMAP SD/MMC: 1
Using default environment
Net: <ethaddr> not set. Validating first E-fuse MAC
cpsw
Hit any key to stop autoboot: 1 ... 0
gpio: pin 53 (gpio 53) value is 1
starting USB...
USB0: Port not available.
switch to partitions #0, OK
mmc0 is current device
mmc found on device 0
Checking for: /boot/uEnv.txt ...
gpio: pin 54 (gpio 54) value is 1
gpio: pin 55 (gpio 55) value is 1
** File not found /boot/zImage **
No kernel found
gpio: pin 54 (gpio 54) value is 0
gpio: pin 55 (gpio 55) value is 0
switch to partitions #0, OK
mmc1(part 0) is current device
mmc found on device 1
** No partition table - mmc 1 **
Checking for: /boot/uEnv.txt ...
gpio: pin 54 (gpio 54) value is 1
** No partition table - mmc 1 **
gpio: pin 55 (gpio 55) value is 1
** No partition table - mmc 1 **
No kernel found
gpio: pin 54 (gpio 54) value is 0
gpio: pin 55 (gpio 55) value is 0
USB is stopped. Please issue 'usb start' first.
USB is stopped. Please issue 'usb start' first.
gpio: pin 54 (gpio 54) value is 0
gpio: pin 55 (gpio 55) value is 0
gpio: pin 56 (gpio 56) value is 1
U-Boot#