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products:sbc:vim1s:development:erase-emmc [2022/08/22 23:05]
hyphop [linux command-line] 		products:sbc:vim1s:development:erase-emmc [2022/08/24 01:59]
hyphop [How-to check boot loaders content]
Line 56: Line 56:
 eMMC boot-loader can be stored on ''/dev/mmcblk0'' and special areas ''/dev/mmcblk0boot0'' or ''/dev/mmcblk0boot0''. eMMC boot-loader can be stored on ''/dev/mmcblk0'' and special areas ''/dev/mmcblk0boot0'' or ''/dev/mmcblk0boot0''.
  
-==== Cleanup all eMMC boot-loaders ====+==== Cleanup eMMC boot loaders ==== 
 + 
 +Cleanup special eMMC boot areas. 
  
 ```sh ```sh
-dd if=/dev/zero count=1 bs=1M | sudo tee /dev/mmcblk?boot? >/dev/null+dd if=/dev/zero count=8192 | sudo tee /dev/mmcblk?boot? >/dev/null
 ``` ```
  
-==== Get block-device names for boot-loaders ====+Also need cleanup eMMC common boot area. 
  
 +```sh
 +sudo dd if=/dev/zero count=2000 seek=1 of=/dev/mmcblk0
 ``` ```
-ls -1 /dev/mmcblk?boot? /dev/bootloader? +
-```+
 <WRAP important > <WRAP important >
 +''/dev/mmcblk0'' eMMC device block name maybe different, please check how-to [[#get-block-device-names-for-boot-loaders]]
 +</WRAP>
  
-''/dev/bootloader?'' is just aliases for ''/dev/mmcblk?boot?''+==== Universal method for cleanup all eMMC boot-areas ====
  
 +```sh
 +sudo dd if=/dev/zero count=8192 | sudo tee /dev/mmcblk?boot? >/dev/null
 +sudo dd if=/dev/zero count=2000 seek=1 of=$(ls /dev/mmcblk?boot?|grep -m1 -o /dev/mmcblk.)
 +
 +```
 +
 +==== Get block device names for boot loaders ====
 +
 +Get block-device names for special boot areas.
 +
 +```shell
 +~$ ls -1 /dev/mmcblk?boot? /dev/bootloader?
 +/dev/bootloader0
 +/dev/bootloader1
 +/dev/mmcblk0boot0
 +/dev/mmcblk0boot1
 +```
 +<WRAP important >
 +''/dev/bootloader?'' same areas as ''/dev/mmcblk?boot?'', but shifted by 512 bytes
 </WRAP> </WRAP>
  
-==== How-to check boot-loaders content ====+Get eMMC block-device name.
  
 ```shell ```shell
-~$ for m in /dev/mmcblk?boot?;do dd if=$m count=1 2>/dev/null | hexdump -C; done +~$ ls -1 $(ls /dev/mmcblk?boot?|grep -m1 -o /dev/mmcblk.) 
 +/dev/mmcblk0 
 +``` 
 + 
 +==== How to check boot loaders content ==== 
 + 
 +This example display empty content for special boot-loaders areas. 
 + 
 +```shell 
 +~$ for m in /dev/bootloader?;do echo $m; dd if=$m count=1 2>/dev/null | hexdump -C ;done  
 + 
 +/dev/bootloader0
 00000000  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................| 00000000  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
 * *
 00000200 00000200
 +/dev/bootloader1
 00000000  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................| 00000000  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
 * *
Line 86: Line 122:
 ``` ```
  
 +Display same but for other boot areas names.
 +
 +```shell
 +~$ for m in /dev/mmcblk?boot?;do echo $m; dd if=$m skip=1 count=1 2>/dev/null | hexdump -C ;done 
 +
 +/dev/mmcblk2boot0
 +00000000  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
 +*
 +00000200
 +/dev/mmcblk2boot1
 +00000000  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
 +*
 +00000200
 +```
 +
 +Next example display valid boot loader header ''@ML''.
 +
 +```shell
 +~$ dd if=/dev/mmcblk0 count=1 skip=1 2>/dev/null | hexdump -C | head -n1
 +00000000  40 4d 4c 20 8d 66 31 ed  00 00 00 00 80 05 00 00  |@ML .f1.........|
 +```
  
 /* /*
Last modified: 2022/08/24 02:00 by hyphop

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