Programming

Yes, back in 2009, after a kernel update to 2.6.26 there was an intermittent and hard to reproduce problem with Intel's e1000e ethernet linux kernel module. It only happened when some specific switches/hubs were connected to the interface; the interface would initialize in an unusable state (about 50% of the computer boots).

The e1000e module was used by a lot of Intel onboard ethernet interfaces, including the one used by Dell Vostro computers.

I found other people reporting it in the kernel's bugzilla, and added my case.

The Intel developer couldn't reproduce it (he didn't have one of the switches that triggered the problem), so he asked me to use bisect to help narrowing down to the commit that started the problem.

Because it was an intermittent issue, I wrote a script to reboot the PC multiple times on each bisect try, to eliminate false positives.

(I didn't remember all these details, but googled my name and bisect, and found the bugzilla thread; it's an interesting bisect use case: https://bugzilla.kernel.org/show_bug.cgi?id=11998#c8 - no I don't mind this associates my lemmy user name with my real name).

The bisect did locate the culprit commit, and after many other tests, it ended up being an issue with the MDI/MDIX (crossover or straight connection detection). The correction was pushed into the kernel.

Bisect definitely helped to find an important and otherwise difficult to find problem there.