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--- products:sbc:vim1s:development:erase-emmc [2022/08/22 02:56]
hyphop [CLI Mode]
+++ products:sbc:vim1s:development:erase-emmc [2022/08/24 01:59]
hyphop [How-to check boot loaders content]
@@ Line 1: / Line 1: @@
-====== VIM1S Erase eMMC ======
+====== VIM1S Erase eMMC bootloader ======
-There are 3 ways to erase the eMMC:
+We have several different ways to erase bootloader.
+=====U-Boot console======
-  * Serial Mode (Developers)
-  * Interrupt Mode
-  * CLI Mode
-<tabbox Serial Mode (Developers)>
   - Connect your PC to the SBC using a [[products:sbc:vim1s:development:setup-serial-tool|Serial Debug Tool]].
@@ Line 48: / Line 44: @@
 ```
-<tabbox Interrupt Mode>
+===== Interrupt Mode =====
 This erasure method is suitable for all products that use the Amlogic SoC:
@@ Line 56: / Line 52: @@
   - Power on your SBC again, and you'll find that all the data on the eMMC has been erased.
-<tabbox CLI Mode>
+===== Linux command-line =====
+eMMC boot-loader can be stored on ''/dev/mmcblk0'' and special areas ''/dev/mmcblk0boot0'' or ''/dev/mmcblk0boot0''.
+==== Cleanup eMMC boot loaders ====
+Cleanup special eMMC boot areas.
+```sh
+dd if=/dev/zero count=8192 | sudo tee /dev/mmcblk?boot? >/dev/null
+```
+Also need cleanup eMMC common boot area.
+```sh
+sudo dd if=/dev/zero count=2000 seek=1 of=/dev/mmcblk0
+```
+<WRAP important >
+''/dev/mmcblk0'' eMMC device block name maybe different, please check how-to [[#get-block-device-names-for-boot-loaders]]
+</WRAP>
+==== 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>
+Get eMMC block-device name.
+```shell
+~$ 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  |................|
+*
+00000200
+/dev/bootloader1
+00000000  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
+*
+00000200
+```
+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.........|
+```
+/*
 This erasure method is suitable for the SBC with Linux installed:
   - Power on and boot up.
   - Open a Terminal, and run ''dd'' to fill your bootloader partition with zeros:
 ```shell
@@ Line 71: / Line 159: @@
 root@Khadas:~# reboot
 ```
-</tabbox>
+*/

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