NVMe SSD minor number 数量 64?

[root@memblaze-lyk1 lyk]# ls -l /dev/nvme0n1

brw-rw---- 1 root disk 259, 0 Jan  5 18:44 /dev/nvme0n1

Documentation/devices.txt

259 block       Block Extended Major

                  Used dynamically to hold additional partition minor

                  numbers and allow large numbers of partitions per device

[root@memblaze-lyk1 linux-stable]# ls /dev/nvme0* -l

crw------- 1 root root  10, 58 Jan  5 18:44 /dev/nvme0

brw-rw---- 1 root disk 259,  0 Jan  5 18:50 /dev/nvme0n1

brw-rw---- 1 root disk 259,  4 Jan  5 18:50 /dev/nvme0n1p1

brw-rw---- 1 root disk 259,  5 Jan  5 18:50 /dev/nvme0n1p2

nvme driver:

#define GENHD_FL_EXT_DEVT                       64 /* allow extended devt */

disk->flags = GENHD_FL_EXT_DEVT