From a242992a320b66e152fb1ba1705f9d8a9bf0313b Mon Sep 17 00:00:00 2001 From: Chris Lamb Date: Wed, 26 Mar 2008 08:19:59 +0000 Subject: hooks/live, scripts/live: Add USB modules, workaround udevtrigger (?) bug This patch goes some way towards fixing USB-backed persistence by configuring the live initramfs to contain the "sd_mod" module and adding a hacky workaround to a udev-related race condition. For some reason, the usual udevtrigger/udevsettle pairing does not block after we have loaded our USB modules and /dev/sda1 (for example) is ready. Because of this, we sleep for a little while and break if a new block device appears. This seems to be a bug either in udev or in my understanding of how the tool is meant to work. Some information may be gained from the casper bug: https://bugs.launchpad.net/ubuntu/+source/casper/+bug/84591 Sleep-based hacks like this are really ugly, but I take some comfort in finding them elsewhere in the source. --- scripts/live | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) (limited to 'scripts') diff --git a/scripts/live b/scripts/live index 7632fc8..797f5df 100755 --- a/scripts/live +++ b/scripts/live @@ -994,6 +994,30 @@ setup_unionfs () # Looking for "${root_persistence}" device or file if [ -n "${PERSISTENT}" ] && [ -z "${NOPERSISTENT}" ] then + # Load USB modules + num_block=$(ls -l /sys/block | wc -l) + for module in sd_mod uhci-hcd ehci-hcd ohci-hcd usb-storage + do + modprobe -q -b ${module} + done + + udevtrigger + udevsettle + + # For some reason, udevsettle does not block in this scenario, + # so we sleep for a little while. + # + # See https://bugs.launchpad.net/ubuntu/+source/casper/+bug/84591 + for timeout in 5 4 3 2 1 + do + sleep 1 + + if [ $(ls -l /sys/block | wc -l) -gt ${num_block} ] + then + break + fi + done + cowprobe=$(find_cow_device "${root_persistence}") if [ -b "${cowprobe}" ] -- cgit v1.2.3