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Make sure you downloaded the latest Intel Manual and got a deep look through it.
Do they actually mean reading the entire intel manual, or just skim and know what is there.... Will the line by line reading of the entire manual help ???
IA-32 Intel? Architecture Software Developer's Manual, Volume 3 alone has 1140 pages. I am not bothered to spend time. But I just wanted to know what is exactly meant.
I'm personally using the Intel 386 Programmers reference manual at first, which is only about 360 pages. This is because mine is just for the 386 for now. I'll add newer stuff later.
well, it will be pretty hard for you to design a proper virtual-memory-manager component for an OS if you don't know how the intel MMU works, for instance. Same for interrupts and the like.
So make at least sure you know what each section is about and make sure you know the details of the things you're currently dealing with. For instance, many people will miss the 'error code' pushed on the stack when an #PG exception is thrown, because they haven't got a deep-enough look at "interrupts and exceptions" chapter, or wonder why their task switching code no longer works once userlevel is enabled...
at least skim, and fully read all the important sections (in fact, i recommend reading (vol.3) twice -- before starting your OS) this is one of the most important references you will ever find, with complete and full explainations of every aspect of the CPU
be sure to make yourself familier with the section numbers, so you find it easier to return to later for reference
the most important sections to study are: 3,4,5,6,16 (chapters 1 & 2 are very helpful for begining)
7,8 will become more important when you get into SMP
chapter 9 is of less relevance to OSdevers (but still an interesting read)
You can probably get away with just skimming it and going mainly by tutorials and trial-by-error and asking many questions on forums. But reading it thoroughly - I too recommend book #3 at least two times before starting work, and #2 once just to get an idea what's available in the instruction set - will allow to make good design decisions, and to avoid the more stupid mistakes.
Writing an OS is similar to writing a device driver - for the CPU. You should know the chip you're programming for, or your product will be lackluster.
Every good solution is obvious once you've found it.
Solar wrote:
Writing an OS is similar to writing a device driver - for the CPU. You should know the chip you're programming for, or your product will be lackluster.
I can add, it's also similar to writing a device. You must know what it's supposed to do and how you want it to do that before you can get it working properly. If you don't decide beforehand what you're going to make, you're going to have to change the ad-hoc decisions you're going to make.
i can remember that first copy of the manual i printed on recycled paper, chapter after chapter, taking them with me on course, and translating them to french (taking notes of the GDT, IDT, paging, etc.) in a spiral notebook when the courses were too boring ::)
kataklinger wrote:
There's a lot of new chapters in newest manual about 64 extensions (separate PDFs) and virtualization
no, most of the 64bit stuff is in the same chapters with the 32bit stuff (though there are a couple new subsections that clarify some 64bit things) but its pretty much integrated together -- you cannot read about one without finding the information on the other
and i do recommend getting the hard copies, as they are easier to use in many ways (though you should have the PDFs also -- they can be searched if you need to -- and more portable if you put it on your PDA )
virtualization though may be separate still (don't know i haven't looked, but its fairly new)
shouldn't be much difference between the intel and AMD manuals, (except of course the few differences -- mostly fast_syscalls, and CPUID)
it is designed to work on both if it is written for one
personally i prefer the layout of Intel vol.3 over AMD vol.2, but thats personal preference, both ISR references have advantages (though i usually use Intel)
i have hard-copies of both, but there aren't many differences in the actual implementation
i don't have either of those documents, just the Intel Manuals, which contain all relevent information (mine is revision 16, 14 doesn't have it)
