Most recent kernel where this bug did *NOT* occur: Unknown Distribution: Ubuntu Hardware Environment: HP Compaq nc6320 Software Environment: Ubuntu, boot time Problem Description: When booting using only battery power, the laptop often expereinces a softlock on CPU#0. Plugging AC in and rebooting seems to be the only cure. Steps to reproduce: Computer off No AC adapter plugged in Power up computer. Bug seems to still occur if the AC is plugged in after initial powerup, but before the softlock. Does not appear to occur with either acpi=off, or apm=off. Booting with acpi=off causes other problems though - see dmesg output for an IRQ11 which noone cared about. Also, the sound card went slightly barmy and repeated the ubuntu startup sound sample over and over.
Created attachment 10101 [details] dmesg output from normal good boot
Created attachment 10102 [details] dmesg output with acpi=off
Created attachment 10103 [details] dmesg output with apm=off
Created attachment 10104 [details] acpidump output from this laptop with a clean boot on ac.
Bug is actually still present with apm=off.
Please replace "quiet" on the cmdline with "debug" boot on battery to reproduce the failure and take a screen shot with a digital camera and attach the .JPG Also, Please try to reproduce the failure with CONFIG_CPU_FREQ=n
It turns out that this softlock is caused by the Intel Wireless driver, and the bug is known: http://bughost.org/bugzilla/show_bug.cgi?id=1096 If powered up with the Wireless radio switched off, the driver would spin trying to get a response from some thermal sensor on the card, which appears to be powered down with the radio off, and the laptop in battery mode. Seems odd that it powers down different bits / behaves differently in battery mode, but thats life. How do I / we close this bug?