Linux 从 /dev/block/mmcblk0 和 /dev/block/mmcblk0p1 读取的区别
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Difference between reading from /dev/block/mmcblk0 and /dev/block/mmcblk0p1
提问by spitfire88
Reading from /dev/block/mmcblk0 returned old data while reading from /dev/block/mmcblk0p1 gave latest data. My question is does linux maintain a back up if data is written to /dev/block/mmcblk0? This is because i was able to read old contents of the SD card by reading through that node.
从 /dev/block/mmcblk0 读取返回旧数据，而从 /dev/block/mmcblk0p1 读取返回最新数据。我的问题是，如果数据写入/dev/block/mmcblk0，linux 是否会保持备份？这是因为我能够通过读取该节点来读取 SD 卡的旧内容。
采纳答案by TheCodeArtist
The mmc sub-system in the Linux kernel registers device nodes of the format mmcblkXpY.
Linux 内核中的 mmc 子系统注册格式为mmcblkXpY.
- Each mmc device registered within the Linux kernel receives it own mmc device number X.
- Each partition on a particular device receives it own number Y
- 在 Linux 内核中注册的每个 mmc 设备都会收到它自己的 mmc 设备编号X。
- 特定设备上的每个分区都有自己的编号Y
Normal file I/O can be performed after mounting a device node pointing to a partition.
挂载指向分区的设备节点后，即可进行正常的文件I/O。
Also note that unless a valid partition table is present on the /dev/mmcblkXdevice, there will be no subsequent /dev/mmcblkXpYnodes on the system.
另请注意，除非/dev/mmcblkX设备上存在有效的分区表，否则/dev/mmcblkXpY系统上不会有后续节点。
