On Mon, Mar 10, 2025 at 01:04:36AM +0900, Simon Richter wrote: > Hi, > > I've built a horrible contraption and received the following output: > > BUG: Unable to handle kernel data access on read at 0xc00a0000000003cc > Faulting instruction address: 0xc00800000dd46484 > Oops: Kernel access of bad area, sig: 11 [#1] > LE PAGE_SIZE=4K MMU=Radix SMP NR_CPUS=2048 NUMA PowerNV > Modules linked in: xe(+) xt_conntrack nft_chain_nat xt_MASQUERADE nf_nat > nf_conntrack_netlink nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 xfrm_user > xfrm_algo xt_addrtype nft_compat x_tables nf_tables libcrc32c nfnetlink > br_netfilter bridge stp llc overlay binfmt_misc evdev joydev hid_generic > usbhid hid cec rc_core drm_gpuvm drm_exec drm_buddy gpu_sched > drm_suballoc_helper drm_display_helper ast drm_ttm_helper ttm snd_hda_intel > drm_shmem_helper snd_intel_dspcfg drm_kms_helper snd_hda_codec snd_hda_core > drm ofpart snd_hwdep snd_pcm xts ipmi_powernv snd_timer ipmi_devintf > powernv_flash snd vmx_crypto gf128mul mtd ipmi_msghandler opal_prd soundcore > at24 drm_panel_orientation_quirks i2c_algo_bit regmap_i2c ext4 crc16 mbcache > jbd2 crc32c_generic dm_mod xhci_pci xhci_hcd tg3 nvme crc32c_vpmsum usbcore > nvme_core libphy usb_common nvme_auth [last unloaded: xe] > CPU: 32 UID: 0 PID: 453 Comm: kworker/32:1 Not tainted > 6.12.12+bpo-powerpc64le #1 Debian 6.12.12-1~bpo12+1 > Hardware name: T2P9D01 REV 1.01 POWER9 0x4e1202 opal:skiboot-9858186 PowerNV > Workqueue: events work_for_cpu_fn > NIP: c00800000dd46484 LR: c00800000dd46384 CTR: 000000003006c394 > REGS: c00020000a637660 TRAP: 0300 Not tainted (6.12.12+bpo-powerpc64le > Debian 6.12.12-1~bpo12+1) > MSR: 9000000000009033 <SF,HV,EE,ME,IR,DR,RI,LE> CR: 24008488 XER: > 20040000 > CFAR: c00800000dd46398 DAR: c00a0000000003cc DSISR: 40000000 IRQMASK: 0 > GPR00: c00800000dd46384 c00020000a637900 c00800000db30600 c00a0000000003cc > GPR04: 0000000000000000 0000000000000004 0000000035c20060 0000000035c20060 > GPR08: 0000000000000000 c00a000000000000 0000000000000000 0000000000008000 > GPR12: 0000000000000000 c0002007ff7ffb00 c00000000017d1cc c000200005d5c200 > GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 > GPR20: 0000000000000000 c0002007fbeeb280 c00800000df35350 c00800000df35700 > GPR24: c00800000df35730 c000200006f60000 0000000000000001 c000200006f61628 > GPR28: 0000000000000001 c0000000027703e0 0000000000000000 c00000000c167000 > NIP [c00800000dd46484] intel_vga_reset_io_mem+0x140/0x188 [xe] > LR [c00800000dd46384] intel_vga_reset_io_mem+0x40/0x188 [xe] > Call Trace: > [c00020000a637900] [c00800000dd46384] intel_vga_reset_io_mem+0x40/0x188 [xe] > (unreliable) > [c00020000a637940] [c00800000dcbbd88] hsw_power_well_enable+0x1f0/0x238 [xe] > [c00020000a637990] [c00800000dcbe470] intel_power_well_enable+0x8c/0xb8 [xe] > [c00020000a637a00] [c00800000dcb6d08] > __intel_display_power_get_domain.part.0+0x98/0xf4 [xe] > [c00020000a637a50] [c00800000dcb9260] intel_power_domains_init_hw+0x94/0x3a8 > [xe] > [c00020000a637af0] [c00800000dcafca4] > intel_display_driver_probe_noirq+0xf4/0x300 [xe] > [c00020000a637b70] [c00800000dc4f124] xe_display_init_noirq+0x80/0x124 [xe] > [c00020000a637ba0] [c00800000dbcee98] xe_device_probe+0x414/0x768 [xe] > [c00020000a637c30] [c00800000dc13370] xe_pci_probe+0x77c/0xc60 [xe] > [c00020000a637d90] [c0000000009f4540] local_pci_probe+0x68/0xf4 > [c00020000a637e10] [c000000000169cdc] work_for_cpu_fn+0x38/0x54 > [c00020000a637e40] [c00000000016ff24] process_one_work+0x1fc/0x4d4 > [c00020000a637ef0] [c000000000170e3c] worker_thread+0x33c/0x504 > [c00020000a637f90] [c00000000017d2fc] kthread+0x138/0x140 > [c00020000a637fe0] [c00000000000de58] start_kernel_thread+0x14/0x18 > Code: ebc1fff0 ebe1fff8 7c0803a6 4e800020 60000000 60000000 60420000 > 3d220000 e9291800 e9290000 386903cc 7c0004ac <8bc903cc> 0c1e0000 4c00012c > 57c9063e > ---[ end trace 0000000000000000 ]--- > > note: kworker/32:1[453] exited with irqs disabled > > The faulting line is > > outb(inb(VGA_MIS_R), VGA_MIS_W); > > in drivers/gpu/drm/i915/display/intel_vga.c > > The 0x3cc offset is VGA_MIS_R, and R9 points to c00a000000000000, where the > I/O ports are mapped -- however the legacy ports don't seem to be active if > the card was never initialized at boot, which it isn't, because the BMC's > VGA emulation is preferred. > > Commenting out the call to intel_vga_reset_io_mem solves the problem, and I > get wonderful 1080p60 output -- but obviously that is not a generic > solution. Hi Simon, thanks for reporting this. Could you please report this to our gitlab issues so we ensure this doesn't get lost on this busy mailing list? https://drm.pages.freedesktop.org/intel-docs/how-to-file-i915-bugs.html Since you are building your own kernel. Would you mind trying to reproduce with latest drm-tip branch from https://gitlab.freedesktop.org/drm/tip I believe Maarten had done some changes on this area lately. Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx> in case he has some quick thoughts... Thanks, Rodrigo. > > Simon
