I normally don't reply but your info here saved me time, THANKS!!!

Key was to mount boot, modify uEnv.txt to disabled HDMI. This is exactly 
what I was looking for so I could use UART5

On Monday, November 25, 2013 11:03:37 AM UTC-5, Zachary Thorson wrote:
>
> I was a bit confused by this at first as well.  The uEnv.txt file in 
> /boot/ is not actually used during the boot process as far as I can tell. 
>  Both the uEnv.txt file and the uboot image used to start the kernel are 
> located on the separate smaller FAT partition on the drive.  So this is the 
> file you will have to change to disable the capes.
>
> For a system without an SDCard (so I can't disable BB-BONE-EMMC-2G) I do 
> the following:
> Normally the BEAGLEBONE media directory auto mounts, but it didn't for 
> this test, so I mounted it manually.
> Also note that if you are using an SD card, you would use mmcblk0p1 
> instead.
>
> root@beaglebone:/# mount /dev/mmcblk0p1 /media/BEAGLEBONE
>
> root@beaglebone:/# ls /media/BEAGLEBONE/
> App  Docs  Drivers  ID.txt  LICENSE.txt  MLO  README.md  START.htm 
>  autorun.inf  u-boot.img  uEnv.txt  uEnv.txt~
>
> root@beaglebone:/# cat /media/BEAGLEBONE/uEnv.txt
> optargs=quiet drm.debug=7 
> capemgr.disable_partno=BB-BONELT-HDMI,BB-BONELT-HDMIN
>
> root@beaglebone:/# cat /sys/devices/bone_capemgr.*/slots
>  0: 54:PF---
>  1: 55:PF---
>  2: 56:PF---
>  3: 57:PF---
>  4: ff:P-O-L Bone-LT-eMMC-2G,00A0,Texas Instrument,BB-BONE-EMMC-2G
>  5: ff:P-O-- Bone-Black-HDMI,00A0,Texas Instrument,BB-BONELT-HDMI
>  6: ff:P-O-- Bone-Black-HDMIN,00A0,Texas Instrument,BB-BONELT-HDMIN
>
> The uEnv.txt on the fat partition can also be edited in Windows when 
> plugging the BBB in via USB.
>
> Zach
>
>
> On Monday, November 25, 2013 6:01:51 AM UTC-6, Yiqing Liang wrote:
>>
>> Hi,
>>
>>    I try to  disable HDMI and emmc by editing the file in /boot/uEnv.txt:
>>
>> optargs=quiet capemgr.disable_partno=BB-BONELT-HDMI,BB-BONE-EMMC-2G
>>
>>
>> Then I reboot , type:
>> cat /sys/devices/bone_capemgr.*/slots
>>
>> See following:
>>
>> Last login: Sat Jan  1 00:00:22 UTC 2000 on ttyGS0
>> root@beaglebone:~# cat /sys/devices/bone_capemgr.*/slots
>>  0: 54:P---L BeagleBone RS232 CAPE,00A1,Beagleboardtoys,BB-BONE-SERL-03
>>  1: 55:PF---
>>  2: 56:PF---
>>  3: 57:PF---
>>  4: ff:P-O-L Bone-LT-eMMC-2G,00A0,Texas Instrument,BB-BONE-EMMC-2G
>>  5: ff:P-O-L Bone-Black-HDMI,00A0,Texas Instrument,BB-BONELT-HDMI
>>
>> With letter L, it means it is still enable.. It does not work.,,
>>
>> So what is wrong, how could I do?
>>
>> I am using latest Angstrom image (2013-06-20)..
>>
>> Also, according to some post in Forum, no matter what I change the dtbo 
>> file in /lib/firmware/  (to disable /enable uart)
>> It has no effect when it reboot.. 
>> I just could change in run time, not in boot time....
>>
>> Yiqing
>>
>

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