I'm apologizing in advance for might be not too clear question's title, I'll try to explain better.
In short, I've started to experience some boot problems, which sometimes result only in longer boot time and sometimes completely prevent the system to load. In the latter case I'm able to see these messages on the screen (and many more):
ata3.00: failed command: IDENTIFY PACKET DEVICE
ata3.00: cmd a1/00:01:00:00:00/00:00:00:00:00/00 tag 0 pio 512 is
res 58/00:02:00:00:02/00:00:00:00:00/00 Emask 0x52 (ATA bus error)
ata3.00: status: ( DRDY DRQ )
******** skipped here *******
INFO: task systemd-udevd:422 blocked for more than 120 seconds.
Not tainted 3.19.0-20-generic #30-Ubuntu
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
There are already some questions on AskUbuntu about problems like mine:
Boot failure: failed: command IDENTIFY PACKET DEVICE
Can I prevent an IDENTIFY PACKET DEVICE command to a specific device at boot?
what I've understood from these is that either my CD-ROM or some controller on the motherboard does not support ATAPI commands and Ubuntu sends them to the device.
But I assembled my computer in 2012 and have not experienced any problems like the current ones.
So I wonder whether this usage of ATAPI was introduced recently (may be 2 to 3 month ago), because, as I can remember, these problems started after some large updates a couple of month ago.
Because if the answer is "no" then something has broken either in my motherboard or CD-ROM.
Thank you in advance.