On Sat 07 May 2022 at 13:50:42 -0400, Ron Georgia wrote:
> This sounds fun, I love testing and troubleshooting, but (no laughing) I
> don't even know what the debug sets are or how to use them. I can look it
> up, and if you have some helpful docs, point me at them and I'll read those
> too.
In short, the debug sets are one option of the installer, of the
"things" you can install (such as base, compiler, X11, ...) , but it's
not included in the default. The set is rather big and it contains
exactly the sort of information that is useful to use with core files:
the correspondence between places in the excutable code and the source
code. With this the debugger can tell you more about what's going on, in
case of a crash. If you have them installed, you have about 1.2GB of
files in /usr/libdata/debug.
On my laptop with NetBSD 9.2/amd64 installed, I have both a wifi and a
wired interface, which both connect to the same network. I made
ifconfig.* files for both of them, with the same content you mentioned;
booting with that dhcpcd seemed to work ok. But a "service dhcpcd
restart" gave me a /dhcpcd.core file, like you.
> Any instructions on how to "read" the dhcpcd.core file to help discover
> where and how it failed?
With the debug files installed, gdb can tell you this sort of stuff:
vargaz:/$ sudo gdb /sbin/dhcpcd /dhcpcd.core
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Reading symbols from /sbin/dhcpcd...
Reading symbols from /usr/libdata/debug//sbin/dhcpcd.debug...
[New process 1]
Core was generated by `dhcpcd'.
Program terminated with signal SIGSEGV, Segmentation fault.
#0 0x000000017e22799f in ipv6nd_applyra (ifp=ifp@entry=0x7bdd4398f100,
ctx=<optimized out>) at /usr/src/external/bsd/dhcpcd/dist/src/ipv6nd.c:628
628 /usr/src/external/bsd/dhcpcd/dist/src/ipv6nd.c: No such file or directory.
(gdb) bt (that's short for backtrace)
#0 0x000000017e22799f in ipv6nd_applyra (ifp=ifp@entry=0x7bdd4398f100,
ctx=<optimized out>) at /usr/src/external/bsd/dhcpcd/dist/src/ipv6nd.c:628
#1 0x000000017e228277 in ipv6nd_handlera (hoplimit=<optimized out>, len=0,
icp=<optimized out>, ifp=0x7bdd4398f100,
sfrom=0x7f7fff05d990 "fe80::a96:d7ff:fea9:5c20", from=<optimized out>,
ctx=0x7f7fff06db10) at /usr/src/external/bsd/dhcpcd/dist/src/ipv6nd.c:1356
#2 ipv6nd_recvmsg (msg=0x7f7fff05d930, ctx=0x7f7fff06db10)
at /usr/src/external/bsd/dhcpcd/dist/src/ipv6nd.c:1814
#3 ipv6nd_handledata (arg=0x7f7fff06db10)
at /usr/src/external/bsd/dhcpcd/dist/src/ipv6nd.c:1866
#4 0x000000017e20b408 in eloop_start (eloop=0x7bdd439e1aa0,
signals=<optimized out>)
at /usr/src/external/bsd/dhcpcd/dist/src/eloop.c:983
#5 0x000000017e23190e in main (argc=<optimized out>, argv=<optimized out>)
at /usr/src/external/bsd/dhcpcd/dist/src/dhcpcd.c:2120
(gdb) print rap
$1 = (struct ra *) 0x7bdd4394acc0
(gdb) print ifp->ctx->ra_routers
$2 = (struct ra_head *) 0x7bdd44832a80
(gdb) print ifp
$3 = (struct interface *) 0x7bdd4398f100
(gdb) print state
$4 = (struct rs_state *) 0x0 # AHA!! state->retrans =... would crash on this!
(gdb) print *ifp
$5 = {ctx = 0x7f7fff06db10, next = {tqe_next = 0x7bdd4398f200,
tqe_prev = 0x7bdd4398f008}, name = "re0", '\000' <repeats 12 times>,
index = 2, active = 2, flags = 4294936643, family = 1 '\001',
hwaddr = "\000&\236\316\214T", '\000' <repeats 13 times>, hwlen = 6 '\006',
vlanid = 0, metric = 202, carrier = 1, wireless = false,
ssid = '\000' <repeats 31 times>, ssid_len = 0,
profile = '\000' <repeats 63 times>, options = 0x7bdd43965440, if_data = {
0x7bdd439e60f0, 0x0, 0x0, 0x0, 0x7bdd439a3140, 0x0, 0x0}}
^0 ^5
(some bits from the source:)
struct rs_state *state = RS_STATE(ifp);
#define RS_STATE(a) ((struct rs_state *)(ifp)->if_data[IF_DATA_IPV6ND])
#define IF_DATA_IPV6ND 5
I don't have the source of 9.2 installed right now, but the crash would
be on line /usr/src/external/bsd/dhcpcd/dist/src/ipv6nd.c:628 in the
function ipv6nd_applyra(). The print commands that I tried were inspired
by the -current version of the ipv6nd_applyra() function, with the
reasoning that maybe the function was not changed, just moved in the
file.
The -current version of dhcpcd is different from the one in 9.2:
line 628 is in function ipv6nd_sortrouters() now and ipv6nd_handlera()
starts at line 661.
It is therefore quite possible that this bug no longer exists in
-current; but I have not tried it.
If you want to puzzle this one out a bit further, there are at least 2
avenues of research possible: get the source from 9.2 and match it up
with the stack trace (do check for yourself you're getting the same one
that I found!), or you can install -current (maybe in a VM?), and try to
reproduce it there.
-Olaf.
--
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