Hi, On Sat, Oct 2, 2010 at 12:38 AM, Sri Ram Vemulpali <[email protected]> wrote: > Hi All, > > I am developing segmentation for my kernel. In that process I > choose to divide whole memory in to fixed size segments. So a 4GB > memory can be divided in to 8192 segments. So I initialize segment > descriptors in to the GTD withs segments base address and limit. Here > base address are 0,0x10000,0x20000,..... and limit is 64kb always for > every segment. For a task if I choose a segment to assign, I will > place the index of that segment descriptor in to CS, DS. Now when > process generates address to put on address bus, then it will do > computation from logical address to linear address. > After processor picks logical address, it chooses segment descriptor > and adds this 32-bit logical address to segment base address to > generate linear address. Now my question is, if my segment size is > 64kb, how is that 32-bit offset is added to segment base address, > which is not right. It should only consider 16-bit offset to add to > base to generate linear address. How can I tell to my processor to > choose only 16-bit offset. Does processor drives offset bit width > automatically based on limit defined in segment descriptor.
You don't have to "tell" your processor to choose only 16-bit offset. If the offset is greater than segment limit an exception will occur. > > Any insight in to this will help me. please clarify my doubt. Waiting > for you reply. > To unsubscribe from this list: send an email with > "unsubscribe kernelnewbies" to [email protected] > Please read the FAQ at http://kernelnewbies.org/FAQ > > @Bond: GTD should be GDT.Also please have a look inside x86 reference manual. thanks, Daniel. -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to [email protected] Please read the FAQ at http://kernelnewbies.org/FAQ
