Hi folk, I'm running a HP Z800 dual processor workstation which has just stopped being able to boot properly due to a recent update. The machine has the latest BIOS available from HP ( this was not changed by the update ). The problem appears to relate to ACPI, and I've been referred here from a post I made to StackExchange. Attempting to boot the machine using any of the available 4.15 kernels ( 4.15.43, 4.15.45, 4.15.47, 4.15.53 ) now gives the following ACPI errors : --- ACPI Error: [CAPD] Namespace lookup failure, AE_ALREADY_EXISTS (20170831/dsfield-212) ACPI Error: Method parse/execution failed \_SB.PCIO._OSC, AE_ALREADY_EXISTS (20170831/psparse-550) --- I usually end up dumped into what I believe is an 'emergency shell'. I have tried a large number of acpi related kernel switches, including 'acpi=ht' and 'acpi_serialize'. The only thing which appears to affect behaviour is 'acpi=off'. This causes a kernel panic, in which case I am not given an emergency shell. I don't know how to grab that info to post here except for taking a screenshot, and not all the info is actually on the screen. So if anyone can suggest a way to further this investigation, I'd be very grateful. What information would be useful to know, and are there any particular experiments I should try, anyone else it would be useful to talk to ? Thanks, Mark de Roussier
