遇到奇怪的现象。启动的时候，dmesg会有一些sr0的读取错误：
root@desktop:~# dmesg|grep sr
[ 0.004794] esrt: Reserving ESRT space from 0x000000006ddb3c98 to 0x000000006ddb3d20.
[ 0.042907] rcu: srcu_init: Setting srcu_struct sizes based on contention.
[ 2.955948] sr 8:0:0:0: [sr0] scsi-1 drive
[ 2.957721] sr 8:0:0:0: Attached scsi CD-ROM sr0
[ 3.008364] sr 8:0:0:0: [sr0] tag#0 FAILED Result: hostbyte=DID_ERROR driverbyte=DRIVER_OK cmd_age=0s
[ 3.008367] sr 8:0:0:0: [sr0] tag#0 CDB: Read(10) 28 00 00 00 ff fc 00 00 02 00
[ 3.008368] I/O error, dev sr0, sector 262128 op 0x0:(READ) flags 0x80700 phys_seg 1 prio class 0
[ 3.058516] sr 8:0:0:0: [sr0] tag#0 FAILED Result: hostbyte=DID_ERROR driverbyte=DRIVER_OK cmd_age=0s
[ 3.058528] sr 8:0:0:0: [sr0] tag#0 CDB: Read(10) 28 00 00 00 ff fc 00 00 02 00
[ 3.058532] I/O error, dev sr0, sector 262128 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 0
[ 3.058584] Buffer I/O error on dev sr0, logical block 32766, async page read
[ 3.059551] sr 8:0:0:0: [sr0] tag#0 FAILED Result: hostbyte=DID_ERROR driverbyte=DRIVER_OK cmd_age=0s
[ 3.059562] sr 8:0:0:0: [sr0] tag#0 CDB: Read(10) 28 00 00 00 04 00 00 00 02 00
但我的机器上并没有光驱，只有一块固态盘和一块硬盘：
root@desktop:~# fdisk -l
Disk /dev/nvme0n1: 238.47 GiB, 256060514304 bytes, 500118192 sectors
...
Disk /dev/sda: 931.51 GiB, 1000204886016 bytes, 1953525168 sectors
...
/dev/下面也没有/dev/sr0的设备文件。
奇怪，这些错误是什么原因？刚才遇到了莫名其妙的一次死机和一次重启，会和这个有关系吗？
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