port-i386/53364: System crashes soon after X server is started with viadrm driver

[vezhlys%gmail.com@localhost]

>Number:         53364
>Category:       port-i386
>Synopsis:       System crashes soon after X server is started with viadrm driver
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    port-i386-maintainer
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Jun 14 08:20:01 +0000 2018
>Originator:     Andrius V
>Release:        8.0 RC1
>Organization:
>Environment:
>Description:
On my VT310-DP motherboard (CN400+VIA VT8237R, UniChrome Pro) I rebuilt the kernel with viadrm driver and started Xorg server (using startx). It starts, you can see graphics environment for few seconds, then system hangs and finally reboots. Crash dump is being generated on next reboot. The issue is not unique to 8 branch. I was facing the same problem on NetBSD 7 as well.

dmesg from crash dump
viadrm0: interrupting at ioapic0 pin 16
uvm_fault(0xc0e8c300, 0xfffff000, 1) -> 0xe
fatal page fault in supervisor mode
trap type 6 code 0 eip 0xc08486e6 cs 0x8 eflags 0x13286 cr2 0xfffffffc ilevel 0 esp 0xdbde5c60
curlwp 0xc3fb1800 pid 107 lid 1 lowest kstack 0xdbde42c0
panic: trap
cpu0: Begin traceback...
vpanic(c0bde197,dbde5b38,dbde5bb4,c01201df,c0bde197,dbde5bc0,dbde5bc0,1,dbde42c0,13286) at netbsd:vpanic+0x121
snprintf(c0bde197,dbde5bc0,dbde5bc0,1,dbde42c0,13286,fffffffc,0,dbde5c60,0) at netbsd:snprintf
trap() at netbsd:trap+0xc80
--- trap (number 6) ---
mutex_oncpu.part.0(c37af114,0,ea000000,0,c0e2cda4,dbde5c68,0,0,dbde5c4c,c01386f6) at netbsd:mutex_oncpu.part.0+0x6
mutex_vector_enter(c3641dc4,200000,c3632000,c3588400,dbde5c8c,c0716e3c,1,dee80000,200000,dbde5c9c) at netbsd:mutex_vector_enter+0x98
via_dma_blit(c3588400,dbde5eac,c4430134,9000,0,1140010,db55c000,c2f379e4,1,4e) at netbsd:via_dma_blit+0x58
drm_ioctl(b400,0,c028644e,dbde5eac,43,c3fb1800,c3fb1800,c028644e,c0e14240,43) at netbsd:drm_ioctl+0x2fc
cdev_ioctl(b400,0,c028644e,dbde5eac,43,c3fb1800,b400,c445a770,c43dc7c0,c445a770) at netbsd:cdev_ioctl+0xbe
spec_ioctl(dbde5d9c,c37af114,c44c6a00,c0bc2dd0,c445a770,c028644e,dbde5eac,43,c43e1480,c028644e) at netbsd:spec_ioctl+0x8b
VOP_IOCTL(c445a770,c028644e,dbde5eac,43,c43e1480,c44589a0,ae800000,c4458aa8,c3764d40,0) at netbsd:VOP_IOCTL+0x3e
vn_ioctl(c43dc7c0,c028644e,dbde5eac,1100000,dbde5f10,c3764d40,dbde5ed0,c081e6aa,28,dbde5eac) at netbsd:vn_ioctl+0x91
sys_ioctl(c3fb1800,dbde5f68,dbde5f60,c3764d40,c3764d40,dbde5f60,dbde5f68,36,0,0) at netbsd:sys_ioctl+0xfc
syscall() at netbsd:syscall+0x1d1
--- syscall (number 54) ---
b42950e7:
cpu0: End traceback...
Type "apropos word" to search for commands related to "word"...
Reading symbols from netbsd.2...(no debugging symbols found)...done.
(gdb) target kvm netbsd.2.core
0xc011dac5 in cpu_reboot ()


From gdb:
#0  0xc011dac5 in cpu_reboot ()
#1  0xc087fa72 in vpanic ()
#2  0xc087fafc in panic ()
#3  0xc01201df in trap ()
#4  0xc0116e48 in alltraps ()
#5  0xdbde5bc0 in end ()
#6  0xc0870010 in cpufreq_register ()
#7  0xc0848813 in mutex_vector_enter ()
#8  0xc071a7be in via_dma_blit ()
#9  0xc07141ff in drm_ioctl ()
#10 0xc08720bf in cdev_ioctl ()
#11 0xc08da506 in spec_ioctl ()
#12 0xc08d2b5c in VOP_IOCTL ()
#13 0xc08cc280 in vn_ioctl ()
#14 0xc0888974 in sys_ioctl ()
#15 0xc0146f41 in syscall ()
#16 0xc010062d in Xsyscall ()
#17 0xdbde5fa8 in end ()
#18 0xba4b00b3 in _KERNEL_OPT_WS_KERNEL_FG ()
#19 0x000000ab in _KERNEL_OPT_WSDISPLAY_SCROLLBACK_LINES ()
#20 0x0025001f in gdt_desc ()
#21 0xba4b001f in _KERNEL_OPT_WS_KERNEL_FG ()
#22 0xc028644e in rtwn_ioctl ()
Backtrace stopped: previous frame inner to this frame (corrupt stack?)
>How-To-Repeat:
Rebuild kernel with viadrm driver.
Boot system with the kernel
startx
>Fix: