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Digging through the MBR (Master Boot Record)
I recently spent some time reading through the grub source code and the real mode assembly that resides in the MBR (master boot record). As I was reading though an explanation of the MBR real mode asembly code, I was amazed at how much cool stuff was packed into the 512-bytes that makes up the MBR (and of that 512-bytes, only 448-bytes are dedicated to storing machine code and error strings). The link above does a great job describing the real mode assembly, and in a nutshell the MBR code in that link does the following four things: The MBR first relocates itself (in the link above, the MBR is relocated to real mode address 0000:6C00). Once the MBR relocates itself, it loops through the partition table to find a partition that is marked active (i.e…
$ read more →PHP security links
While reading up on PHP security, I came across several links that I thought I would pass on: Security Focus article on securing PHP installations: Article on PHP attack vectors and defenses: Bugtraq discussion on PHP security:
$ read more →First thoughts of CentOS 4.0
I was recently introduced to CentOS 4.0, which is a Linux distribution built from the source RPMs that comprise Redhat Advanced Server. I am currently running several production services on CentOS 4.0, and am extremely happy with the features it brings to the table. Here are several reasons you might be interested in using CentOS: 1. CentOS 4.0 is free, and has the look and feel of Redhat Advanced Server…
$ read more →Managing packages with yum
If you are interested in using yum to manage packages on Linux servers, you might be interested in my article managing packages with yum. If you have comments or feedback, let me know.
$ read more →My new domain
After reading UNIX file systems, I got to be a bit of a file system junkie. The book does a good job of covering file system design, the block I/O interfaces, caching, the VFS and VNODE abstractions, and the implementation of FFS, VxFS and EXT3. The book piqued my interest in file systems, so I started doing some research on intelligent I/O schedulers and prefetch algorithms. Performing this research has helped me on numerous occassions with understand how to tailor workloads for a given file system and storage subsystem…
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