On 27/04/10 12:34, Paul Sutton wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > Thomas Ibbotson wrote: >>[...] >> I'm running 64-bit Lucid with 4GB of RAM, however Lucid is only seeing >> 3.1GB. It may be I have to set something in BIOS I haven't had time to >> look into it fully yet, but be aware that it might not just see your >> 6GB straight off. >> >> Tom >> > Would some of the missing memory be video memory perhaps which is > shared, from the main memory.
Hello, Paul and Thomas. It's not the memory that's shared, it's the address space: You need to set the BIOS to enable memory mapping around the 4GiB 'hole' for exactly the reason that Paul said. The 1GB of physical memory above 3GiB is remapped above 4GiB leaving a 'hole' where peripherals can be memory-mapped. It's not possible for a 32-bit process to address beyond 4GiB, but PAE (Physical Address Extension) enables a 32-bit kernel to access memory above 4GiB. Using a 64-bit Linux all 64-bit processes and the kernel itself can address > 4GiB. However, 'legacy' processes using the ia32 libraries would still be limited to ~3GiB. HTH, Tony. -- Dr. A.J.Travis, University of Aberdeen, Rowett Institute of Nutrition and Health, Greenburn Road, Bucksburn, Aberdeen AB21 9SB, Scotland, UK tel +44(0)1224 712751, fax +44(0)1224 716687, http://www.rowett.ac.uk mailto:a.tra...@abdn.ac.uk, http://bioinformatics.rri.sari.ac.uk/~ajt -- ubuntu-uk@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-uk https://wiki.ubuntu.com/UKTeam/
