users of drm-legacy-kmod or drm drivers from base - panic in intel_gmch_probe(), debug symbols?

[Marcin Cieslak]

On Sun, 8 Mar 2020, Niclas Zeising wrote:

> If you are using these legacy drivers, I'm also very interested in hearing 
> what issues you are facing that prevents you from using the new lkpi based 
> drivers.

I am using base modules from FreeBSD 11.3 simply because
drm-fbsd11.2-kmod 4.11g20200221 panics for me:

https://github.com/FreeBSDDesktop/kms-drm/issues/225#

(in short: intel_gmch_probe() looks unfinished to me).

Besides, how do I build drm-fbsd11.2-kmod to have full debug symbols included?

make WITH_DEBUG=yes install seems not enough:

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This GDB was configured as "amd64-marcel-freebsd"...

Unread portion of the kernel message buffer:
instruction pointer	= 0x20:0xffffffff82d995a0
stack pointer	        = 0x28:0xfffffe011cec3340
frame pointer	        = 0x28:0xfffffe011cec3350
code segment		= base 0x0, limit 0xfffff, type 0x1b
 			= DPL 0, pres 1, long 1, def32 0, gran 1
processor eflags	= interrupt enabled, resume, IOPL = 0
current process		= 1059 (kldload)
trap number		= 12
panic: page fault
cpuid = 1
KDB: stack backtrace:
#0 0xffffffff80b5cda7 at kdb_backtrace+0x67
#1 0xffffffff80b1589e at vpanic+0x17e
#2 0xffffffff80b15713 at panic+0x43
#3 0xffffffff80fa5730 at trap_pfault+0
#4 0xffffffff80fa5779 at trap_pfault+0x49
#5 0xffffffff80fa4e0d at trap+0x29d
#6 0xffffffff80f84613 at calltrap+0x8
#7 0xffffffff82d994f4 at intel_gmch_probe+0xd4
#8 0xffffffff82cc39e2 at i915_gmch_probe+0x42
#9 0xffffffff82cc3677 at i915_ggtt_probe_hw+0x47
#10 0xffffffff82c97450 at i915_driver_init_hw+0x60
#11 0xffffffff82c96dcf at i915_driver_load+0x14f
#12 0xffffffff82cea97b at i915_pci_probe+0xbb
#13 0xffffffff82eff944 at linux_pci_attach+0x4d4
#14 0xffffffff80b4efac at device_attach+0x39c
#15 0xffffffff80b50b09 at bus_generic_driver_added+0x89
#16 0xffffffff80b4ccca at devclass_driver_added+0x7a
#17 0xffffffff80b4cc35 at devclass_add_driver+0x135
Uptime: 4m32s
Dumping 384 out of 3984 MB:..5%..13%..21%..34%..42%..55%..63%..71%..84%..92%

Reading symbols from /boot/kernel/aesni.ko...Reading symbols from /usr/lib/debug//boot/kernel/aesni.ko.debug...done.
done.
Loaded symbols for /boot/kernel/aesni.ko
Reading symbols from /boot/kernel/geom_eli.ko...Reading symbols from /usr/lib/debug//boot/kernel/geom_eli.ko.debug...done.
done.
Loaded symbols for /boot/kernel/geom_eli.ko
Reading symbols from /boot/kernel/zfs.ko...Reading symbols from /usr/lib/debug//boot/kernel/zfs.ko.debug...done.
done.
Loaded symbols for /boot/kernel/zfs.ko
Reading symbols from /boot/kernel/opensolaris.ko...Reading symbols from /usr/lib/debug//boot/kernel/opensolaris.ko.debug...done.
done.
Loaded symbols for /boot/kernel/opensolaris.ko
Reading symbols from /boot/kernel/cuse.ko...Reading symbols from /usr/lib/debug//boot/kernel/cuse.ko.debug...done.
done.
Loaded symbols for /boot/kernel/cuse.ko
Reading symbols from /boot/kernel/linux.ko...Reading symbols from /usr/lib/debug//boot/kernel/linux.ko.debug...done.
done.
Loaded symbols for /boot/kernel/linux.ko
Reading symbols from /boot/kernel/linux_common.ko...Reading symbols from /usr/lib/debug//boot/kernel/linux_common.ko.debug...done.
done.
Loaded symbols for /boot/kernel/linux_common.ko
Reading symbols from /boot/kernel/tpm.ko...Reading symbols from /usr/lib/debug//boot/kernel/tpm.ko.debug...done.
done.
Loaded symbols for /boot/kernel/tpm.ko
Reading symbols from /boot/modules/vboxdrv.ko...done.
Loaded symbols for /boot/modules/vboxdrv.ko
Reading symbols from /boot/kernel/fdescfs.ko...Reading symbols from /usr/lib/debug//boot/kernel/fdescfs.ko.debug...done.
done.
Loaded symbols for /boot/kernel/fdescfs.ko
Reading symbols from /boot/kernel/tmpfs.ko...Reading symbols from /usr/lib/debug//boot/kernel/tmpfs.ko.debug...done.
done.
Loaded symbols for /boot/kernel/tmpfs.ko
Reading symbols from /boot/modules/vboxnetflt.ko...done.
Loaded symbols for /boot/modules/vboxnetflt.ko
Reading symbols from /boot/kernel/netgraph.ko...Reading symbols from /usr/lib/debug//boot/kernel/netgraph.ko.debug...done.
done.
Loaded symbols for /boot/kernel/netgraph.ko
Reading symbols from /boot/kernel/ng_ether.ko...Reading symbols from /usr/lib/debug//boot/kernel/ng_ether.ko.debug...done.
done.
Loaded symbols for /boot/kernel/ng_ether.ko
Reading symbols from /boot/modules/vboxnetadp.ko...done.
Loaded symbols for /boot/modules/vboxnetadp.ko
Reading symbols from /boot/kernel/linux64.ko...Reading symbols from /usr/lib/debug//boot/kernel/linux64.ko.debug...done.
done.
Loaded symbols for /boot/kernel/linux64.ko
Reading symbols from /boot/kernel/linprocfs.ko...Reading symbols from /usr/lib/debug//boot/kernel/linprocfs.ko.debug...done.
done.
Loaded symbols for /boot/kernel/linprocfs.ko
Reading symbols from /boot/modules/i915kms.ko...done.
Loaded symbols for /boot/modules/i915kms.ko
Reading symbols from /boot/modules/drm.ko...done.
Loaded symbols for /boot/modules/drm.ko
Reading symbols from /boot/kernel/linuxkpi.ko...done.
Loaded symbols for /boot/kernel/linuxkpi.ko
Reading symbols from /boot/modules/linuxkpi_gplv2.ko...done.
Loaded symbols for /boot/modules/linuxkpi_gplv2.ko

(kgdb) bt
#0  doadump () at pcpu.h:234
#1  0xffffffff80b154b8 in kern_reboot (howto=260) at /usr/src/sys/kern/kern_shutdown.c:388
#2  0xffffffff80b158d8 in vpanic (fmt=<value optimized out>, ap=<value optimized out>) at /usr/src/sys/kern/kern_shutdown.c:784
#3  0xffffffff80b15713 in panic (fmt=<value optimized out>) at /usr/src/sys/kern/kern_shutdown.c:715
#4  0xffffffff80fa5730 in trap_fatal (frame=<value optimized out>, eva=<value optimized out>) at /usr/src/sys/amd64/amd64/trap.c:899
#5  0xffffffff80fa5779 in trap_pfault (frame=0xfffffe011cec3280, usermode=0) at pcpu.h:234
#6  0xffffffff80fa4e0d in trap (frame=0xfffffe011cec3280) at /usr/src/sys/amd64/amd64/trap.c:438
#7  0xffffffff80f84613 in calltrap () at /usr/src/sys/amd64/amd64/exception.S:288
#8  0xffffffff82d995a0 in readl () from /boot/modules/i915kms.ko
#9  0xffffffff82d994f4 in intel_gmch_probe () from /boot/modules/i915kms.ko
#10 0xffffffff82cc39e2 in i915_gmch_probe () from /boot/modules/i915kms.ko
#11 0xffffffff82cc3677 in i915_ggtt_probe_hw () from /boot/modules/i915kms.ko
#12 0xffffffff82c97450 in i915_driver_init_hw () from /boot/modules/i915kms.ko
#13 0xffffffff82c96dcf in i915_driver_load () from /boot/modules/i915kms.ko
#14 0xffffffff82cea97b in i915_pci_probe () from /boot/modules/i915kms.ko

Despite mobing /boot/kernel/i915km.ko and /boot/kernel/drm.ko away, I do not seem to
get enough symbols for a nice backtrace.

However, I have managed to analyse a problem a bit with the machine code, see the GitHub ticket for details.

Marcin
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