@@ -149,6 +149,7 @@ On each development board, you need to partition the memory to store the precedi
| root | /dev/ram0 (Hi3516DV00) , root=PARTUUID=614e0000-0000 rw (rk3568) | Boot device loaded by the kernel.|
| rootfstype | ext4 | Type of the root file system.|
| default_boot_device | soc/10100000.himci.eMMC | (Recommended information) Default boot device. In the first phase of the boot process, a soft link will be created for the required device based on this field.|
| ohos.required_mount.xxx | /dev/block/platform/soc/10100000.himci.eMMC/by-name/xxx@/usr@ext4@ro,barrier=1@wait,required | The fstab information is first read from cmdline. If this fails, the system will try to read the information from the **fstab.required** file.|
- Mounting of required partitions
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@@ -179,7 +180,7 @@ On each development board, you need to partition the memory to store the precedi
- Mapping with **default_boot_device**
The kernel writes **bootargs** information to **/proc/cmdline**. The information includes **default_boot_device**, which specifies the primary device directory required for system boot.
The kernel writes **bootargs** information to **/proc/cmdline**. The information includes **default_boot_device**, which specifies the primary device directory required for system boot. The content prefixed with **ohos.required_mount.** is the partition mounting information required for system boot. It should be the same as that in the **fstab.required** file. In addition, the block device node in the partition mounting information should be a device node pointed by the soft link under **by-name** in the **default_boot_device** directory. For example, if the value of **default_boot_device** is **soc/10100000.himci.eMMC**, then the value of **ohos.required_mount.system** contains **/dev/block/platform/soc/10100000.himci.eMMC/by-name/system**, which is the soft link pointing to the system device node.
During creation of a block device node, the device path will be matched against the value of **default_boot_device**. If the matching is successful, a soft link pointing to the real block device node will be created in **/dev/block/by-name**. In this way, device node access is made irrelevant to the chip platform.
