Public bug reported:
I think that when booting from a USB 2.0 thumb drive using the
"toram" kernel boot parameter, the "cp" command that copies the live-
media to RAM returns before the copy has completed.
I am booting Ubuntu from a thumb drive. The thumb drive contains
parts of Ubuntu Live-CD's. I am able to boot the 32-bit and 64-bit
versions of Ubuntu 14.04 in Legacy-BIOS mode. I can boot the 64-bit
version in EFI mode.
When I try to boot either version of Ubuntu, in either BIOS mode,
with the "toram" kernel boot parameter, the boot fails: I see the
console message that it is about to copy the live-media to RAM. After
about 10 seconds I get a burst of messages that look like it just
rediscovered my external USB disk. After another 60 to 80 seconds of
the light on the thumb drive flickering madly, I get a burst of console
messages, too fast to read, ending with an "(initramfs)" prompt. The
last message before the prompt says it couldn't find "/sbin/init", and
maybe I should try the "init" boot parameter.
From the "(initramfs)"/Busybox prompt, I can see a small set of
directories (maybe the "initrd"?). There is a "/cdrom", but it's empty
-- i.e., it is NOT attached to my thumb drive. There is a "/var", but
no "/var/log". The only log file I can find is a "casper.log" in the
"/" directory.
There is a "/root" directory. It contains "/root/cdrom", on which
"/dev/shm" is mounted -- this contains a complete copy of the contents
of my thumb drive.
I have tried adding debug print to the script "casper", checking
the contents of the live-media "casper" directory on the thumb drive
before the copy, and checking the contents of the corresponding
directory on the tmpfs device after the copy. I tried checking again
after a "sync", and again after a "sleep 100". The right files are
there before the copy. Nothing seems to be there on the destination
device after the copy, after the sync, or after the sleep.
My main reason for thinking the "cp" command is returning too soon
is the way the boot seems to proceed before the thumb drive has stopped
blinking. If the burst of messages about discovering the external USB
drive are coming from another process, then I don't know anything.
I have another thumb drive, this one USB 3.0, with the same
versions of Ubuntu. I can boot either the 32-bit or the 64-bit version
in Legacy-BIOS mode, with or without the "toram" option. This is
another reason I think it has to do with the speed of the USB 2.0 thumb
drive.
** Affects: casper (Ubuntu)
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/1530018
Title:
casper boot toram fails from USB 2.0
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