[OpenWrt-Devel] AA on brcm47xx: Unhandled kernel unaligned access
n-a-zhubr at yandex.ru
Fri Jun 20 16:12:40 EDT 2014
I have asus wl-500W router (http://wiki.openwrt.org/toh/asus/wl500w). It
is also very similar to wl-500gp.
Some few months ago I updated to 12.09. I can't recall now if it was
backfire or kamikaze before, but I noticed 2 things immediately:
1. Maximum practically achievable download speed increased somewhat.
(From ~30Mbit to ~34mbit approx)
2. After reaching (and keeping) this max download speed, the device will
always reboot soon. (Absolutely reproducible)
For some time I was thinking that's just hardware, like bad electrolytic
capacitors and/or weak power supply. Finally I opened the router,
replaced all 3 capacitors (2 of 3 appeared somewhat damaged indeed),
attached a voltmeter to check for undervoltage. Still nothing: power
supply is OK, reboots still happen.
So I had to turn to the software side, and found 2 new things again:
1. While uplink load goes up approaching 34Mbit, softirqs eat up more
and more CPU, approaching 100% CPU.
2. At some point I get (on a serial link):
[ 368.948000] sched: RT throttling activated
[ 382.688000] Unhandled kernel unaligned access[#1]:
[ 382.932000] Kernel panic - not syncing: Fatal exception in interrupt
[ 382.940000] Rebooting in 3 seconds..
(Trimmed all in between because there is no debugging info for now)
I suppose this is something that should not normally happen, and I'd
like to have it fixed somehow. I haven't tried trunk yet, but I will, if
it could make some difference. I can provide serial logs, compile trunk,
apply patches, redo testing etc. (As time permits)
Any hints appreciated.
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