[Fedora-ia64-list] arp

[Luck, Tony]

> With arp command on my NovaScale 4040 server Itanium 2, messages are 
> displayed:
> [root at diane-int6 ~]# arp -a
> arp(9654): unaligned access to 0x60000fffff922f3e, ip=0x400000000000a820
> arp(9654): unaligned access to 0x60000fffff922f46, ip=0x400000000000a860
> ? (172.31.255.1) at 00:06:D6:6E:40:09 [ether] on eth0
> 
> Normal ? debugging mode ?

This is normal for the ia64 kernel ... it reports on user processes
that get unaligned access faults (the reports are rate limited so as
not to flood the system logs, so these messages may not show all the
unaligned access faults that a program actually incurs).

We do this because taking faults and emulating the unaligned access in
the kernel is slow (hundreds of cycles) so it is good to alert users
that they are not getting the performance that they should.

Things you can do about this if you don't like to see these messages:

1) Fix the program that is making the unaligned access.  This is the
   best solution.

2) Disable printing of the messages when you execute a program:
   $ prctl --unaligned=silent arp -a

3) Disable system-wide reporting of the messages (very recent kernels only):
   # echo 1 > /proc/sys/kernel-ignore-unaligned-usertrap

-Tony