[lkml]   [2006]   [Dec]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [PATCH] connector: Some fixes for ia64 unaligned access errors
On Sat, 2006-12-09 at 18:34 -0800, Pete Zaitcev wrote:
> On Sat, 9 Dec 2006 15:09:13 -0600, Erik Jacobson <> wrote:
> > > Please try to declare u64 timestamp_ns, then copy it into the *ev
> > > instead of copying whole *ev. This ought to fix the problem if
> > > buffer[] ends aligned to 32 bits or better.
> >
> > So I took this suggestion for a spin and met with the same result.
> > The unaligned access messages are still produced.
> I see. And I see you went a few steps forward with dignosing it:
> > dbg fork after timespec_to_ns call, b4 memcpy
> > kernel unaligned access to 0xe000003076b6fbe4, ip=0xa0000001004f1480
> > dbg fork after memcpy, b4 other ev settings...
> > a0000001004f1470 <proc_fork_connector+0x1f0> [MMI] ld8 r40=[r14]
> > a0000001004f1476 <proc_fork_connector+0x1f6> ld8 r38=[r38]
> > a0000001004f147c <proc_fork_connector+0x1fc> nop.i 0x0;;
> > a0000001004f1480 <proc_fork_connector+0x200> [MIB] st8 [r39]=r40
> > a0000001004f1486 <proc_fork_connector+0x206> nop.i 0x0
> > a0000001004f148c <proc_fork_connector+0x20c> b0=a0000001000a36c0 <printk>;;

I'm not very familiar with ia64 asm but it looks like its loading and
storying 8 bytes at a time for the memcpy().

> It seems rather strange that memcpy gets optimized this way. I could
> not have foreseen it. Still, it was worth a try, even if putting 32
> extra bytes on stack and running memcpy on them does not seem too
> onerous, for a fork(). Thanks for doing it, and let's go with your
> original patch then... if Matt Helsley does not mind.

OK, I'll ack the original.

> Thank you,
> -- Pete

I'm shocked memcpy() introduces 8-byte stores that violate architecture
alignment rules. Is there any chance this a bug in ia64's memcpy()
implementation? I've tried to read it but since I'm not familiar with
ia64 asm I can't make out significant parts of it in


-Matt Helsley

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

 \ /
  Last update: 2006-12-12 00:55    [W:0.067 / U:70.564 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site