** Description changed: - -----BEGIN PGP SIGNED MESSAGE----- - Hash: SHA1 - - affects ubuntu/lucid lynx - - Seeing following error message when booting Lucid Lynx daily builds - from USB stick. + Seeing following error message when booting from live installer. /init: line 7: can't open /dev/sr0: No medium found - Boots ok - using DELL Inspiron 1501 laptop with 2gb Ram + == Explanation == - I get same error if image written to disk with - * USB Startup Disk Creator - * Create DELL recovery media - * Unetbootin + This continues to affect desktop installers for 17.10 and 18.04. - all three packages return same error so looks like ISO at fault ? + There are a variety of underlying causes and the message seen isn't + related to the cause, which causes immense confusion. - see http://ubuntuforums.org/showthread.php?t=1345125 + As soon as the kernel has booted it executes the /init script in the + /casper/initrd.lz initial ramdisk. - -----BEGIN PGP SIGNATURE----- - Version: GnuPG v1.4.9 (GNU/Linux) - Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ + One of the first things the /scripts/casper functions do is find the + installer device in order to mount it's file-system. As part of that + they scan various block devices looking for it, in a repeating loop. + Each time through the loop existing devices get re-scanned. One device + that is scanned is the CD/DVD drive, usually /dev/sr0. - iEYEARECAAYFAks3kkYACgkQRT+RNEgk9JhxQACfT9zIpm/O8NPk/gNVKoy+JftF - 574An1lZaOutT1kVQFbqjF98bgJMIcfv - =cOYl - -----END PGP SIGNATURE----- + When booting from USB any CD/DVD drive usually has no disc inserted and + therefore we see repeated + + /init: line 7: can't open /dev/sr0: No medium found + + each time the loop runs. + + There are many reasons why the installer file-system isn't found but + here is a way to narrow down the cause: + + 1. The above message repeats rapidly many times in succession until the + screen is filled with the same line and eventually it drops to the + Busybox initramfs shell prompt. + + This means the USB mass storage device wasn't detected, or the + usb_storage kernel module wasn't loaded by the kernel. This could be + because the udev rules didn't match the device and therefore didn't + create the device node (e.g. /dev/sdb) + + 2. The above message only appears once, or only repeats after long + delays, and it takes many minutes to drop to the Busybox initramfs shell + prompt. + + This indicates the udev daemon is hung whilst processing device + detection rules, possibly due to it executing an external command which + has hung. There are some calls to 'udevadm trigger' which has a default + delay of 120 seconds if the kernel event queue isn't drained - which it + may not be if some process/task has hung. + + 3. The device doesn't present on a device node or path the casper + scripts look for. + + Setting the kernel command-line option live-media= (e.g: live- + media=/dev/mmcblk0) which can be supported with live-media-path= (e.g: + live-media-path=/casper) which is a directory where the live file system + is, (e.g: by default /casper/filesystem.squashfs) + + There may be other indirect causes of these headline symptoms. + + I've just dealt with one where the UEFI boot failed in this way from a + USB flash mass storage device. After hours helping the user diagnose it, + the solution was to move the USB device from the rear USB port of the + motherboard to a front port! + + Some years ago I had a similar issue on Dell Poweredge servers where the + CD-ROM device with the installer on was a true SCSI device on a SCSI + controller, and the installer was not shipped with or loading the + correct kernel module for that SCSI controller. + + Systems with a Floppy disk controller but no floppy disk attached can + also cause long timeouts as the FDC ports are probed and a long timeout + expires before the OS decides there is no FDD attached.
-- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/500822 Title: /init: line 7: can't open /dev/sr0: No medium found To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+bug/500822/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
