Re: RAM shows less

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| Date: Mon, 10 May 2010 21:14:20 +0530
| From: Jatin K <ssh.fedora@xxxxxxxxx>
| 
| On Monday 10 May 2010 08:29 PM, Bill Davidsen wrote:
| > Jatin K wrote:
| >    
| >> Dear All
| >>
| >> I've a new Dell Inspiton 1564 laptop with 1GB graphics card and 4GB DDR3
| >> RAM, FC 12 64bit installed on it , but in system information tab it
| >> shows 3.7GB usable RAM. My Question is "what about the remaining RAM ??"
| >> is it shared with graphics card ? then what is the meaning of dedicated
| >> RAM of my graphics card ( if graphics card shares my installed ram module )
| >>
| >> any idea ??
| >>
| >>      
| > Look at the start of /var/log/messages, /proc/mtrr, etc. See if your CPU has PAT
| > capability, etc.
| >
| >    
| Thnx Bill
| 
| My processor is Intel i5 430 2.27Ghz  ( turbo boost up to 2.53Ghz)
| 
| and following is the output of  cat /proc/mtrr
| ---------------------------------------------------------------------------------------
| reg00: base=0x0ffe00000 ( 4094MB), size=    2MB, count=1: write-protect
| reg01: base=0x000000000 (    0MB), size= 2048MB, count=1: write-back
| reg02: base=0x080000000 ( 2048MB), size= 1024MB, count=1: write-back
| reg03: base=0x100000000 ( 4096MB), size= 1024MB, count=1: write-back
| reg04: base=0x138000000 ( 4992MB), size=  128MB, count=1: uncachable
| -----------------------------------------------------------------------------------------

reg00: 2MiB of ROM?
reg01 + reg02 + reg03: 4G of RAM
reg04: 128MiB of video frame buffer?  uncachable.

Why is the frame buffer only 128MiB when you say that you have a 1G?

Why does reg03 overlap with reg04?

end of reg03's range: 4096 + 1024 = 5120;  
end of reg04's range: 4992 + 128 = 5120

So: reg04 overlaps with reg03 and covers the last 128MiB of reg03's
range.

Linux didn't much like overlapping MTRR ranges.  It may be OK now
that PAT is used by most X video controller drivers.

(The problem is that video drivers usually want their memory to be
write-combining and overlapping write-through and write-combining
MTRRs isn't legal.  If PAT is used instead of MTRR for setting the
write-combining option, I think that it works.)

As far as RAM goes, you seem to have
	4096MiB - 128MiB
	= 3968MiB
	= 3.875GiB
	= 4063232KiB
	= 4160749568B

| following[1] is the output of "free  " command
|              total       used       free     shared    buffers     cached
| Mem:       3917912    1113388    2804524          0      39296     319600
| -/+ buffers/cache:     754492    3163420
| Swap:      4805624          0    4805624

So: you are still missing 145,320 KiB of RAM.  I have no idea if that
is to be expected.
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