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--- products:sbc:vim1s:development:erase-emmc [2022/08/22 23:34]
hyphop
+++ products:sbc:vim1s:development:erase-emmc [2022/08/24 02:00] (current)
hyphop old revision restored (2022/08/23 15:37)
@@ Line 56: / Line 56: @@
 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
-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
 ```
@@ Line 67: / Line 67: @@
 ```sh
-sudo dd if=/dev/zero count=100 seek=1 of=/dev/mmcblk0
+sudo dd if=/dev/zero count=2000 seek=1 of=/dev/mmcblk0
 ```
 <WRAP important >
-''/dev/mmcblk0'' maybe different, please check it
+''/dev/mmcblk0'' maybe different, please check how-to [[#get-block-device-names-for-boot-loaders]]
 </WRAP>
+==== Universal method for cleanup all eMMC boot-areas ====
-==== Get block-device names for boot-loaders ====
+```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=$(ls /dev/mmcblk?boot?|grep -m1 -o /dev/mmcblk.)
+```
+==== Get block-device names for boot loaders ====
 Get block-device names for special boot areas.
@@ Line 86: / Line 93: @@
 /dev/mmcblk0boot1
 ```
+<WRAP important >
+''/dev/bootloader?'' same areas as ''/dev/mmcblk?boot?'', but shifted by 512 bytes
+</WRAP>
 Get eMMC block-device name.
@@ Line 94: / Line 104: @@
 ```
-<WRAP important >
+==== How-to check boot loaders content ====
-''/dev/bootloader?'' is just aliases for ''/dev/mmcblk?boot?''
+This example display empty content for special boot-loaders areas.
-</WRAP>
+```shell
+~$ for m in /dev/bootloader?;do echo $m; dd if=$m count=1 2>/dev/null | hexdump -C ;done
-==== How-to check boot-loaders content ====
+/dev/bootloader0
+00000000  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
+*
+00000200
+/dev/bootloader1
+00000000  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
+*
+00000200
-This example display empty content for special boot-loaders areas.
+```
+Display same but for other boot areas names.
 ```shell
-~$ for m in /dev/mmcblk?boot?;do dd if=$m count=1 2>/dev/null | hexdump -C; done
+~$ 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  |................|
 *
@@ Line 114: / Line 137: @@
 ```
-Next example display valid boot-loader header ''@ML''.
+Next example display valid boot loader header ''@ML''.
 ```shell
-~$ dd if=/dev/mmcblk2 count=1 skip=1 2>/dev/null | hexdump -C | head -n1
+~$ 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.........|
 ```

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