Kernel only detection 2 GB of memory on AMD

[Vincent Stemen]

On Mon, Mar 01, 2010 at 08:50:47PM -0800, Matthew Dillon wrote:
>     Hmm.  Do a verbose boot and post the dmesg output.  Lets see what
>     memory list the kernel gets from the BIOS.
> 
> 						-Matt

OK.  Here are the parts in /var/log/messages that seem to have anything
to do with memory.  I assume you didn't want the whole output (it's
long) but I could provide it if you need.

    kernel: CPU: AMD Opteron(tm) Processor 246 (2004.56-MHz 686-class CPU)
    kernel: Origin = "AuthenticAMD"  Id = 0xf5a  Stepping = 10
    kernel:
    Features=0x78bfbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CLFLUSH,MMX,FXSR,SSE,SSE2>
    kernel: AMD Features=0xe0500800<SYSCALL,NX,MMX+,LM,3DNow!+,3DNow!>
    kernel: Data TLB: 32 entries, fully associative
    kernel: Instruction TLB: 32 entries, fully associative
    kernel: L1 data cache: 64 kbytes, 64 bytes/line, 1 lines/tag, 2-way associative
    kernel: L1 instruction cache: 64 kbytes, 64 bytes/line, 1 lines/tag, 2-way associative
    kernel: L2 internal cache: 1024 kbytes, 64 bytes/line, 1 lines/tag, 16-way associative
    kernel: real memory  = 2147418112 (2047 MB)
    kernel: Physical memory chunk(s):
    kernel: 0x00001000 - 0x0009efff, 647168 bytes (158 pages)
    kernel: 0x008da000 - 0x7ffdffff, 2138071040 bytes (521990 pages)
    kernel: avail memory = 2065563648 (1969 MB)
    kernel: ACPI MADT: RSDP not in EBDA
    kernel: ACPI MADT: RSDP in BIOS mem
    kernel: ACPI MADT: MADT in XSDT
    kernel: ACPI MADT: LAPIC address 0xfee00000, flags 0x1
    ...

Also,

New information.  We tested various memory configurations.
Dragonfly correctly detected 4 GB of memory with only one of them.

Total RAM
---------
5G      4 x 1G in each slot on one cpu and 4 x 256M in each slot on the
        other cpu.
        bios reported 5G, dragonfly reported 4G (correct: 32 bit kernel)

        * This is the only combination where DF sees 4 GB *

4G      4 x 1G all slots on one cpu
        bios reported 4G, dragonfly reported 2G
        
        This is weird.  Same configuration as above but remove the 256M
        RAM's from the slots for the other cpu and it no longer
        detects all the RAM on the first cpu.

4G      1G in slots 0 and 2 on each cpu
        bios reported 4G, dragonfly reported 3G

4G      2 x 1G in slots 0 and 1 on each cpu.
        bios reported 4G, dragonfly reported 2G

5G      2 x 1G slots 0 and 1 + 2 x 256M in slots 2 and 3  on each cpu
        bios reported 5G, dragonfly reported 2G

--
- Vince