Bingo! That did it.
I copied/modified the #ifdef from tulip_core.c:
/* Set the copy breakpoint for the copy-only-tiny-buffer Rx structure. */
#if defined(__alpha__) || defined(__arm__) || defined(__hppa__) \
|| defined(CONFIG_SPARC) || defined(__ia64__) \
|| defined(__sh__) || defined(__mips__)
static int rx_copybreak = 1518;
#else
static int rx_copybreak;
#endif
And that seems to have worked like a champ.
Thanks for the help. I knew I was asking for problems by using
non-Digital hardware in an Alpha :).
-Dustin
Ivan Kokshaysky wrote:
On Sun, Jul 08, 2007 at 03:29:35PM -0700, Andrew Morton wrote:
This problem does NOT seem to affect my Tsunami/Shark (EV68AL) box running the
same kernel version on the same LAN. Not sure if it's CPU generation related
(EV5 vs EV6), or if it's the NIC (via_rhine on the EV5 vs e100 on the EV6).
It is the NIC, I suppose.
I don't think there's necessarily a bug here: that's just the kernel
telling us that there are unaligned accesses which got successfully
fixed up, so we're being perhaps a bit inefficient. Yes?
Sort of. It's not exactly a bug, just an old and well known problem
with ethernet controllers that can do DMA only at 32-bit boundaries,
so the IP headers are not properly aligned. A workaround is to
disable "rx_copybreak" feature, either by passing "rx_copybreak=1536"
to the driver, or add #ifdef to via_rhine.c, like tulip, starfire and
many other drivers have:
/*
* Set the copy breakpoint for the copy-only-tiny-frames scheme.
* Setting to > 1518 effectively disables this feature.
*
* NOTE:
* The ia64 doesn't allow for unaligned loads even of integers being
* misaligned on a 2 byte boundary. Thus always force copying of
* packets as the starfire doesn't allow for misaligned DMAs ;-(
* 23/10/2000 - Jes
*
* The Alpha and the Sparc don't like unaligned loads, either. On Sparc64,
* at least, having unaligned frames leads to a rather serious performance
* penalty. -Ion
*/
#if defined(__ia64__) || defined(__alpha__) || defined(__sparc__)
static int rx_copybreak = PKT_BUF_SZ;
#else
static int rx_copybreak /* = 0 */;
#endif
Ivan.
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