many (i can say "all" for me) kernel unaligned accesses happen in the netfilter code. so if u r running a firewall of any kind on EV56 u have a real problem. i wrote a small stupid (but working perfectly) patch that eliminates them to zero. if interessted just ask and i will post it (again)
Linux alpha 2.4.23-grsec #2 Tue Dec 2 22:05:21 CET 2003 alpha unknown 20:54:17 up 7 days, 18:38, 8 users, load average: 1.00, 1.00, 1.00 (dont care about the load the box is used for searching for big primes and the load is just OK) cpu : Alpha cpu model : EV56 cpu variation : 0 cpu revision : 0 cpu serial number : Linux_is_Great! system type : Miata system variation : 0 system revision : 0 system serial number : MILO-2.2-17 cycle frequency [Hz] : 433061852 est. timer frequency [Hz] : 1024.00 page size [bytes] : 8192 phys. address bits : 40 max. addr. space # : 127 BogoMIPS : 860.60 kernel unaligned acc : 0 (pc=0,va=0) user unaligned acc : 27 (pc=120305e88,va=1204ceae4) platform string : N/A cpus detected : 0 the box is also my internet gateway and runs NAT and statefull packet filter as u can see no kernel un acc`s at all some in userspace, but thats ok the box is rock stable even under nonstop 100% load (i had to reboot because of power failure a week ago) the box gets hot as hell! cheers, Juraj Holtak On Sunday 29 February 2004 18:10, Falk Hueffner wrote: > Kelledin <[EMAIL PROTECTED]> writes: > > Lately I've been looking closely at the compile logs on my EV56 > > box, and I've noticed a particular gcc warning occurring > > frequently: > > > > cast increases required alignment of target type. > > > > This worries me almost as much as casts between integers and > > pointers of different size, but...even with all the warnings, I > > don't get too many crashes. > > Well, not surprising, since this will only lead to a problem if a) the > pointer is actually dereferenced and b) the alignment is actually > wrong. Often this cannot occur and the warning is bogus. > > > Still, I'm compelled to wonder about the effect of unaligned > > accesses, i.e. how severe is an unaligned access in user-space? How > > about in kernel-space? How does the system handle them? > > A trap to PALcode occurs and the firmware hands over to the operating > system. The OS emulates the access and resumes the program. Takes > probably about 100-200 cycles. > > > I have a pretty clear idea what it would take to fix that warning > > condition, but it occurs so frequently that I'm not sure it would be > > worth the time. :/ > > I don't think so, unless you actually see unaligned accesses in the > syslog. > > -- > Falk