Hello, Helge. On Fri, Feb 02, 2024 at 09:41:38AM +0100, Helge Deller wrote: > In a second step I extended your patch to print the present > and online CPUs too. Below is the relevant dmesg part. > > Note, that on parisc the second CPU will be activated later in the > boot process, after the kernel has the inventory. > This I think differs vs x86, where all CPUs are available earlier > in the boot process. > ... > [ 0.000000] XXX workqueue_init_early: possible_cpus=ffff present=0001 online=0001 ... > [ 0.228080] XXX workqueue_init: possible_cpus=ffff present=0001 online=0001 ... > [ 0.263466] XXX workqueue_init_topology: possible_cpus=ffff present=0001 online=0001 So, what's bothersome is that when the wq_dump.py script printing each cpu's pwq, it's only printing for CPU 0 and 1. The for_each_possible_cpu() drgn helper reads cpu_possible_mask from the kernel and iterates that, so that most likely indicates at some point the cpu_possible_mask becomes 0x3 instead of the one used during boot - 0xffff, which is problematic. Can you please sprinkle more printks to find out whether and when the cpu_possible_mask changes during boot? Thanks. -- tejun
