Finding the right needle in the kernel haystack

This post details the process of debugging a segfault in the `mpt2sas` driver on a new Dell PowerEdge C5220 server when using Debian GNU/Linux. The issue was traced to a significant difference between the Debian Squeeze kernel's driver (based on Linux 2.6.32) and the RHEL6 kernel's driver (backported from Linux 3.4). The author successfully identified a specific 7-line patch ([ebda4d38df542e1ff4747c4daadfc7da250b4fa6](http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=ebda4d38df542e1ff4747c4daadfc7da250b4fa6)) in the later driver that resolved the segfault. This patch was then applied to the Debian kernel, enabling the use of the new hardware.