4 GB RAM showing up as 3, BIOS memory hole and all that

[Daniel Rock]

Steve Kargl wrote:
> On Mon, Aug 15, 2005 at 12:56:57PM -0400, Martin Cracauer wrote:
>>Any way to get my GB back?
> 
> 
> This should be a FAQ.  No, you can't get it back.
> David O'brien has explained this more than once in 
> the freebsd-amd64 list.  Unfortunately, I don't
> have a handy URL for you to read.  I suggest scanning
> the list for posts by David in the Feb to May timeframe. 
> 

Hmm,

on my board I could get the missing hole back. BIOS has three settings 
for memory hole remapping: Disabled/Hardware/Software (Hardware 
remapping should only work on stepping E-Opterons).

With each of these settings I get different results:

Hardware:
real memory  = 5637144576 (5376 MB)
Physical memory chunk(s):
0x0000000000001000 - 0x0000000000090fff, 589824 bytes (144 pages)
0x0000000000985000 - 0x00000000a616ffff, 2776543232 bytes (677867 pages)
0x0000000100000000 - 0x000000014ffdffff, 1342046208 bytes (327648 pages)
avail memory = 4109500416 (3919 MB)

Software:
real memory  = 6442450944 (6144 MB)
Physical memory chunk(s):
0x0000000000001000 - 0x0000000000090fff, 589824 bytes (144 pages)
0x0000000000985000 - 0x000000007ff1ffff, 2136584192 bytes (521627 pages)
0x0000000100000000 - 0x0000000174baffff, 1958412288 bytes (478128 pages)
avail memory = 4085907456 (3896 MB)

Disabled:
real memory  = 2951872512 (2815 MB)
Physical memory chunk(s):
0x0000000000001000 - 0x0000000000090fff, 589824 bytes (144 pages)
0x0000000000983000 - 0x00000000aac56fff, 2855092224 bytes (697044 pages)
avail memory = 2846003200 (2714 MB)


Unfortunately, only if I cut memory below 4GB, my nve network adapter 
does work at all (ehm, mostly) - but that is another story...



Daniel