GDT

[slacker]

does it really matter if the accessed bit is set to 1 when i set up my GDT?

[Pype.Clicker]

no. that's a write-only bit for the cpu. It will never read or use its value. It just fills it with a 1 when it accesses the segment so that the software can keep track of segment useage and optionnally implement segments-based virtual memory (swapping out a whole code segment from memory when it's no longer used).

no need to say that paging-based virtual memory has been preferred by OS designers.

[slacker]

what does the available for system software bit do?

[Tim]

Nothing. It's available for use by system software (hence the name). You can use it for whatever you want.