这些 "SATA link down"消息是什么意思？

Issue

• 系统日志中看到的"SATA link down"消息是什么意思：

libata version 3.00 loaded.
ata_piix 0000:00:1f.2: version 2.12
ACPI: PCI Interrupt 0000:00:1f.2[A] -> GSI 16 (level, low) -> IRQ 217
ata_piix 0000:00:1f.2: MAP [ P0 P2 P1 P3 ]
ata_piix 0000:00:1f.2: 0x1F0 IDE port busy
PCI: Setting latency timer of device 0000:00:1f.2 to 64
ata1: DUMMY
ata2: SATA max UDMA/133 bmdma 0x60f8 irq 15
GSI 26 sharing vector 0x82 and IRQ 26
ACPI: PCI Interrupt 0000:00:1f.5[C] -> GSI 21 (level, low) -> IRQ 130
ata_piix 0000:00:1f.5: MAP [ P0 -- P1 -- ]
PCI: Setting latency timer of device 0000:00:1f.5 to 64
ata3: SATA max UDMA/133 cmd 0x6108 ctl 0x6124 bmdma 0x60d0 irq 130
ata4: SATA max UDMA/133 cmd 0x6100 ctl 0x6120 bmdma 0x60d8 irq 130
ata3: SATA link down (SStatus 0 SControl 300)
ata4: SATA link down (SStatus 0 SControl 300)

• 系统上的 DVD 驱动器突然变为不可用。如何解决这个问题？

    kernel: ata2: exception Emask 0x50 SAct 0x0 SErr 0x4090800 action 0xe frozen
    kernel: ata2: irq_stat 0x00400040, connection status changed
    kernel: ata2: SError: { HostInt PHYRdyChg 10B8B DevExch }
    kernel: ata2: hard resetting link
    kernel: ata2: SATA link down (SStatus 1 SControl 300)
    kernel: ata2: hard resetting link
    kernel: ata2: SATA link down (SStatus 0 SControl 300)
    kernel: ata2: limiting SATA link speed to 1.5 Gbps
    kernel: ata2: hard resetting link
    kernel: ata2: SATA link down (SStatus 1 SControl 310)
    kernel: ata2.00: disabled
    kernel: ata2: EH complete
    kernel: ata2.00: detaching (SCSI 1:0:0:0)

• 当连接到磁盘设备有一些问题时，SATA 链接断开事件消息会被记录，并且驱动程序需要重置连接这些设备的链接。它们似乎是一些与硬件相关的问题。

• 在引导时检测到 SATA 硬盘不可靠。