#484 Disable agp driver in kernel config (kernel panic on zpool import)

[doktornotor]

I thought it'd be good to raise this ticket here before you release v14.

On OPNsense, multiple people using random old hardware did hit a bug which triggers kernel panic when you do env ZPOOL_IMPORT_PATH=/dev zpool import -Na

That command in turn seems to poke everything under /dev and triggers some bug in completely dead agp driver code, triggering agp_close() call - which ends up with a kernel panic like this:

panic: page fault
cpuid = 0
time = 1724410401
KDB: stack backtrace:
db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame 0xfffffe0064e3e818
vpanic() at vpanic+0x131/frame 0xfffffe0064e3e940
panic() at panic+0x43/frame 0xfffffe0064e3e9a0
trap_fatal() at trap_fatal+0x48b/frame 0xfffffe0064e3ea00 trap_pfault() at trap_pfault+0x46/frame 0xfffffe0064e3ea50
calltrap() at calltrap+0x8/frame 0xfffffe0064e3ea50
trap 0xc, rip = 0xffffffff804d7de7, rsp = 0xfffffe0064e3eb20, rbp = 0xfffffe0064e3eb40
agp_close() at agp_close+0x57/frame 0xfffffe0064e3eb40 giant_close() at giant_close+0x68/frame Bxfffffe0064e3eb98
devfs_close() at devfs_close+0x4b3/frame 0xfffffe0064e3ec00
VOP_CLOSE_APV() at VOP_CLOSE_APV+0x1d/frame 0xfffffe0064e3ec20
vn_close1() at vn_close1+0x14c/frame 0xfffffe0064e3ec90
vn_closefile() at vn_closefile+0x3d/frame 0xfffffe0064e3ece0
devfs_close_f() at devfs_close_f+0x2a/frame 0xfffffe0064e3ed18
_fdrop() at_fdrop+0x11/frame Bxfffffe0064e3ed30
closef() at closef+0x24a/frame 0xfffffe0064e3edco
closefp_impl() at closefp_imp1+0x58/frame 0xfffffe0064e3ee00 amd64_syscall() at amd64_syscall+0x100/frame 0xfffffe0064e3ef30
fast_syscall_common() at fast_syscall_common+Bxf8/frame 0xfffffe0064e3ef30
syscall (6, FreeBSD ELF64, close), rip = 0x3843e84152ba, rsp = 0x3843f837fd8
18 , rbp = 0x3843f837fda0
KDB: enter: panic
[ thread pid 31 tid 100232 ]
Stopped at
kdb_enter+8x33: movq $0,0xfd9962(%rip)
NEC
db>

How much insane the zpool import is remains up to debate, however I would say I'd be good to eliminate the possibility of hitting this unfortunate code path on XigmaNAS altogether by nuking the offending unmaintained driver from the kernel. If someone still needs it, they can use the module from FreeBSD on their own risk.

Cheers.