OSDev.org

Hi,

I am wondering what is usually in the first few pages of one OS, after it already switched to protected mode? Is it still the real-mode interrupt table from the BIOS, and BIOS code???

Lets not consider a special OS, but the usual OS, such as BSD, Linux or Windows. Any idea?

Thanks.

Hi,

It depends. The first page of physical memory will contain an IVT, but if you know you will not need any real mode code, you can use it as a normal page, if you like. This may cause problems if your page frame allocator uses NULL to indicate a problem, though!

The BDA and EBDA will be in the same place that they were before in physical memory too. If you are using paging, this need not be apparent to any running apps.

Cheers,
Adam