Farul M. Ghazali said: > If your user-space app is compiled as a 64-bit binary, it will see >4GB of > RAM (or whatever your RAM + swap is). If your app is a 32-bit binary, it > will see al the 4GB of RAM it can actually address, but nothing more. > However, the 32-bit binaries don't have to share the 4GB address space wih > other processes unlike what you're seeing with a 32-bit kernel/machine > now. Note that this is assuming you're running a 64-bit kernel of course. > Cmpiling 64-bit apps was a bit confusing at first (mixing 32-bit and > 64-bit libs during linking, etc.) but we got the hang of it after a while. What OS are you using? I have SuSE 9.1 64bit on a dual Opteron with 4 gigs of RAM. BIOS *sees* all 4 gigs, but SuSE with the 2.6.4 64bit kernel only sees 3.19 gigs. -- Jeremy Mann jeremy@biochem.uthscsa.edu University of Texas Health Science Center Bioinformatics Core Facility http://www.bioinformatics.uthscsa.edu Phone: (210) 567-2672