Re: [tlug] Docked Laptop Dilemma

[Tobias Diedrich <ranma@example.com>]

David J Iannucci wrote:
> Unfortunately I've never been very much successful in this, *apparently*
> (it seems to me) because the OS is "talking" to various external devices
> (primarily the monitor, but also possibly USB devices, etc), and if it
> "wakes up" and finds those devices gone, it tends to have a negative
> reaction, and need rebooting in short order.  Mind you, I haven't tried
> this too recently, and don't have clear memories of exactly what went
> wrong, only that it always did.  I tend not to take my laptop to
> meetings for this reason (which is probably good because it's easier to
> pay attention), and it's never particularly painful that I can't.....
> but it seems like it ought to be something doable, and that some geeks
> somewhere have figured out how to do.

On my X41 the ACPI hardware signature changes when I add or remove
USB devices while in hibernate.  And at least recent Linux kernels
panic if the signature changes during sleep.
Currently I'm using a three-liner patch:

Index: linux-2.6.31-rc3/drivers/acpi/sleep.c
===================================================================
--- linux-2.6.31-rc3.orig/drivers/acpi/sleep.c	2009-07-15 14:35:21.924278562 +0200
+++ linux-2.6.31-rc3/drivers/acpi/sleep.c	2009-07-15 14:49:15.694290601 +0200
@@ -492,8 +492,7 @@
 	/* Check the hardware signature */
 	if (facs && s4_hardware_signature != facs->hardware_signature) {
 		printk(KERN_EMERG "ACPI: Hardware changed while hibernated, "
-			"cannot resume!\n");
-		panic("ACPI S4 hardware signature mismatch");
+			"resuming anyway!\n");
 	}
 	/* Restore the NVS memory area */
 	hibernate_nvs_restore();