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mp floating point structure and the ebda
Posted: Fri Jan 02, 2004 12:00 am
by dr_watts
So I was reading the MP 1.4 spec about finding the MP FP structure... first of all, why couldn't it just be in an assigned spot like everything else? But anyway, it says one of the places this could be stored is in the Extended Bios Data Area. Now this is all well and good except that I don't know how to find that.
Anybody have any ideas?
Thanks
RE:mp floating point structure and the ebda
Posted: Fri Jan 02, 2004 12:00 am
by DaveHK
Some BIOS' reserve additional ram at the top of memory in addition to the bios data area at 0x400, if this is used then the pointer to the top of ram (usually at 640KB) will be moved down in RAM. offset 13h in the BDA (linear address 0x413) will indicate the top of ram in kilobytes, this normally contains the value 64, but if lower, then everything from this value (x 1024) to 640 K is considered EBDA and must also be searched for the MPS structure