Hi Jonathan, I got this boot error when testing kernel in kvm, built with the attached config: [ 7.618723] kobject: 'tpci200' (ffff8800072f8798): kobject_add_internal: parent: 'drivers', set: 'drivers' [ 7.620602] kobject: 'tpci200' (ffff8800072f8798): kobject_uevent_env [ 7.621875] kobject: 'tpci200' (ffff8800072f8798): fill_kobj_path: path = '/bus/pci/drivers/tpci200' [ 7.623739] BUG: unable to handle kernel NULL pointer dereference at 00000000000000b0 [ 7.625237] IP: [] iio_buffer_register+0x27/0x4b0 [ 7.626396] PGD 0 [ 7.626839] Oops: 0000 [#1] PREEMPT SMP [ 7.627591] CPU 1 [ 7.628027] Pid: 1, comm: swapper/0 Not tainted 3.5.0-rc5+ #36 [ 7.629191] RIP: 0010:[] [] iio_buffer_register+0x27/0x4b0 [ 7.630569] RSP: 0018:ffff88000008de30 EFLAGS: 00010202 [ 7.630569] RAX: ffff8800072f8c58 RBX: 0000000000000000 RCX: 0000000000000000 [ 7.630569] RDX: 0000000000000005 RSI: ffffffff81c2b580 RDI: ffff8800072f9008 [ 7.630569] RBP: ffff88000008dea0 R08: 0000000000003a84 R09: 000000000000fffe [ 7.630569] R10: 000000000000000a R11: 0000000000000001 R12: ffff8800072f9008 [ 7.630569] R13: 0000000000000134 R14: 0000000000000000 R15: ffff8800072f9008 [ 7.630569] FS: 0000000000000000(0000) GS:ffff88000de00000(0000) knlGS:0000000000000000 [ 7.630569] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b [ 7.630569] CR2: 00000000000000b0 CR3: 0000000001a0b000 CR4: 00000000000006e0 [ 7.630569] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 7.630569] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 [ 7.630569] Process swapper/0 (pid: 1, threadinfo ffff88000008c000, task ffff88000008a000) [ 7.630569] Stack: [ 7.630569] ffffffff81e7f3ba 0000000000000000 ffff88000008de70 ffffffff810ac628 [ 7.630569] ffff88000008de80 ffff8800072f95e8 ffffffff818d425b ffffffff81c2b580 [ 7.630569] ffff88000008dea0 0000000000000000 ffff8800072f9008 0000000000000134 [ 7.630569] Call Trace: [ 7.630569] [] ? tpci200_drvr_init_module+0x29/0x29 [ 7.630569] [] ? debug_mutex_init+0x48/0x70 [ 7.630569] [] ? tpci200_drvr_init_module+0x29/0x29 [ 7.630569] [] iio_dummy_init+0x163/0x1ed [ 7.630569] [] do_one_initcall+0xb6/0x1c8 [ 7.630569] [] kernel_init+0x20c/0x2fd [ 7.630569] [] ? loglevel+0x46/0x46 [ 7.630569] [] kernel_thread_helper+0x4/0x10 [ 7.630569] [] ? do_one_initcall+0x1c8/0x1c8 [ 7.630569] [] ? gs_change+0x13/0x13 [ 7.630569] Code: 00 00 00 00 55 48 89 e5 41 57 49 89 ff 41 56 41 55 41 54 53 48 83 ec 48 4c 8b b7 f8 02 00 00 48 83 05 9d 13 30 01 01 48 89 75 c8 <49> 8b 86 b0 00 00 00 48 85 c0 74 22 8b 8f 78 05 00 00 48 63 f1 [ 7.630569] RIP [] iio_buffer_register+0x27/0x4b0 [ 7.630569] RSP [ 7.630569] CR2: 00000000000000b0 [ 7.671281] ---[ end trace 2659a79bb8841e3c ]--- [ 7.672239] Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000009 Thanks, Fengguang