Wednesday, May 02, 2007

Driver problems

Well, as promised, yesterday a) the maintenance guy came and swapped out my kitchen faucet, and b) I signed the lease renewal on my current iceberg dock. Ah well.

The following EMAIL was sent by an engineer to a techical support person. Names have been changed to protect the guilty.

The problem is that the MAC filter in the network chip is not being properly programmed by the driver under certain circumstances, thus cutting off traffic because the MAC filter is set up for a MAC that our software isn't listening for anymore (generally the original hardware MAC). The purpose of the hardware MAC filter in the network chip is to reduce the number of network interrupts coming into the system to improve system performance, but in this case it's reducing it to zero! I know that version 1.0.1 had the issue. I *believe* it was fixed for 1.0.2, but Abel was the person formally responsible for the fix and Baker or Charlie would have done the code review on the fix and thus know what release it made it into, I'll need to check to make sure. Anyhow, tcpdump "wakes it up" because tcpdump turns off the MAC filter by placing the network driver into promiscuous mode. This "works", but kills system performance.

If you have the 1.0.2 release notes handy you might want to take a look at them. I will be in the office in an hour or so depending upon what the crazy automobile drivers are doing (I looked outside and the road is wet so there may be freeway clogs) and if the 1.0.2 release notes do not answer your question I will be able to verify for certain whether the fix made it into 1.0.2 via looking at the CVS change logs. Hmm, yes, the freeways have driver problems too. Unfortunately the freeway driver problem isn't fixable with a driver fix, unless you consider forced sterilization of bad drivers via branding iron prior to reproduction to be a "hot fix", which unfortunately has a very long debug cycle time to verify the proper operation of the hot fix and thus isn't feasible no matter how attractive a hot fix it appears on some mornings.

Branding irons. Fixing bad drivers with. Prior to reproduction. I like!

-- Badtux the Bad-driver-hatin' Penguin

Posted by BadTux at 5/02/2007 09:25:00 AM
Labels: ,

1 comment:

Ground rules: Comments that consist solely of insults, fact-free talking points, are off-topic, or simply spam the same argument over and over will be deleted. The penguin is the only one allowed to be an ass here. All viewpoints, however, are welcomed, even if I disagree vehemently with you.

WARNING: You are entitled to create your own arguments, but you are NOT entitled to create your own facts. If you spew scientific denialism, or insist that the sky is purple, or otherwise insist that your made-up universe of pink unicorns and cotton candy trees is "real", well -- expect the banhammer.

Note: Only a member of this blog may post a comment.

Subscribe to: Post Comments (Atom)