Welcome to the dark corner of BIOS reverse engineering, code injection and various modification techniques only deemed by those immensely curious about BIOS

Saturday, July 30, 2011

Memory Management in Legacy BIOS

Memory management during POST in "legacy" BIOS is not well known to most system programmers. Probably, only a handful knows that this kind of routine even exists. Perhaps, you would ask why would anyone need a memory manager in BIOS level? Well, as you know, memory space in 16-bit environment is scarce. Moreover, BIOS modules are getting bigger and if all of them loaded at the same time to the 1 MB space available in 16-bit mode, we will run out of space very easily. The solution is obviously a memory manager. But, how would you go about creating a memory manager while everyone are developing propietary BIOS codes? As in other branch of software development. You create a standard interface for the memory manager, leaving out the details to implement the standard to the BIOS vendors. This is exactly what happens.

The standard for memory management during POST in BIOS code execution is the Post Memory Manager (PMM) specification. The document for this specification is rather hard to come by. PMM is a relatively short specification.

An in-depth coverage of the subject is currently in preparation for an upcoming article at the Pinczakko Official Website.

Facebook Comment Feature Now Available

Hi guys, Facebook commenting is now enabled in this blog. I hope this enables better communication with the blog audience. Another news is that I'm going to do cross-referencing to Pinczakko Official Website from here. I'm back to writing articles now that it has been several years dormant. The last article I wrote was on the DLL support in Award BIOS. Well, it has been a long time ago.

Wednesday, July 20, 2011

The Long Silence and News on the Second Edition Book

Hi guys. It's been a very long silence since March. Well, real life got in the way. I was busy with a middleware project and the need to learn from scratch made it very difficult to allocate time for the BIOS research. Well, now I'm back researching BIOS again full-throttle at least 3 days per week. Therefore, the book content would be coming in the coming weeks hopefully. I have several semi-official works in BIOS baking in the kitchen. You will see some of it in the new book. Just FYI, the first book took 5 years for the research because I'm complete noob in (believe it or not) computer. Not just programming but using computer as well. It took several years just to learn to write Windows Device Drivers for experiments. Certainly a lot has changed since those years. Therefore, several months of research I think would be sufficient this time around as long as I can keep my "mood level" and "focus" to finish this one. Thanks for the suggestions in my post from last March. I'm preparing a reworked ToC to accomodate those ideas. Regarding my plan to release the first edition of the book for free. I'm still doing some cautious reading on the contract to see whether it will violate my contract or not. Actually, I stopped receiving royalties in mid-2010. However, I don't want to violate any IP transferred to my publisher as per the contract.