Author Topic: Bypass inserted microsd during boot  (Read 4170 times)

Offline vlemo

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Bypass inserted microsd during boot
« on: June 27, 2013, 01:36:05 pm »
I have 2 cbb one with sandisk ultra inserted and nand flash with debian os., the second also is flashed with the same os and a microsd of an other brand. Both microsd's are ext4 formatted with no boot partitiion. The first cbb boots from nand bypassing the inserted ultra microsd and mounting the ultra microsd as data disk. The second cbb does not boot while the microsd is inserted and only boots when de microsd is pulled out. When I insert that microsd during startup the microsd is mounted as data disk.

How can I bypass booting from inserted microsd's? Any suggestions would be welcome.
« Last Edit: June 27, 2013, 01:38:38 pm by vlemo »

Offline patwood

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Re: Bypass inserted microsd during boot
« Reply #1 on: June 27, 2013, 04:22:13 pm »
Zero out the first few 100K of the SD card and repartition; if this card was used previously for booting a linux image, there are magic numbers on it outside the first partition (after the partition table).  You can also zero out the space betweeen the partition table and the first partition if you can determine what that is.  For example, on my SD card, the partition table, SPI, and uboot take up the first 1MB, so to zero it out, I do:

Code: [Select]
dd if=/dev/zero of=/dev/mmcblk0 bs=512 seek=1 count=2047

Offline vlemo

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Re: Bypass inserted microsd during boot
« Reply #2 on: June 28, 2013, 02:19:48 am »
Thx, it worked.