Re: F7 64bit 4G Memory

[Srikanth Konjarla <srikanth.konjarla@xxxxxxxxx>]

Marcelo,

Thanks for the links. First, i think PAE is for 32 bit kernel and 
second, it is needed if you have more than 4G (>4G). My machine does not 
fall under any category.

Srikanth

Marcelo de Souza Sant'Anna wrote:
> Read this too:
>
> http://fedora.kiewel-online.de/repoview/linux/releases/7/Everything/i386/repodata/repoview/kernel-PAE-0-2.6.21-1.3194.fc7.html
>
>
> On Mon, 2007-07-02 at 22:37 -0400, Srikanth Konjarla wrote:
> > Thanks for the response. Interestingly, i could not find any BIOS 
> > options pertaining to memory.
> >
> > I found the following.
> >
> > # cat /proc/mtrr
> > reg00: base=0xfeda0000 (4077MB), size= 128KB: write-back, count=1
> > reg01: base=0xfff00000 (4095MB), size=   1MB: write-protect, count=1
> > reg02: base=0x00000000 (   0MB), size=2048MB: write-back, count=1
> > reg03: base=0x80000000 (2048MB), size=1024MB: write-back, count=1
> > reg04: base=0xc0000000 (3072MB), size= 256MB: write-back, count=1
> >
> > Could be incompatible memory modules or something?
> >
> > Thanks
> >
> > Srikanth
> >
> > Wolfgang S. Rupprecht wrote:
> > > Srikanth Konjarla <srikanth.konjarla@xxxxxxxxx <mailto:srikanth.konjarla@xxxxxxxxx>> writes:
> > >> I am running F7 in 64-bit mode on a laptop. I have upgraded the memory
> > >> from 3G to 4G (Bios confirms it) but kernel sees only 3.2G (i have
> > >> passed mem=4096M kernel parameter). Wondering if i am missing anything
> > >> here.
> > > 
> > > What you are missing is the really nasty design of IBM-PC legacy
> > > memory allocations.  ;-)
> > > 
> > > Play around in your BIOS and see if you can map the excess memory
> > > above 4GB.  Often the labels for the settings will have the term
> > > "MTRR" in the name.  When you get it right "cat /proc/mtrr" should
> > > show the extra 750MBytes mapped above 4 Gigs.  The setting names might
> > > not make much sense (at least they don't on my Tyan).  You might need
> > > to just try them all and see what effect they have on the linux mttr
> > > settings.  Here is what it looks like on my board when I have it set
> > > to see all 4 GBytes:
> > > 
> > > $ cat /proc/mtrr 
> > > reg00: base=0x00000000 (   0MB), size=2048MB: write-back, count=1
> > > reg01: base=0x80000000 (2048MB), size=1024MB: write-back, count=1
> > > reg02: base=0xc0000000 (3072MB), size= 256MB: write-back, count=1
> > > reg03: base=0xcff00000 (3327MB), size=   1MB: uncachable, count=1
> > > reg04: base=0x100000000 (4096MB), size= 512MB: write-back, count=1
> > > reg05: base=0x120000000 (4608MB), size= 256MB: write-back, count=1
> > > reg06: base=0xd8000000 (3456MB), size= 128MB: write-combining, count=2
> > > 
> > > Notice the first 3 entries are 3.25 GBytes (reg00, reg01 and reg02).
> > > The last 0.75GBytes are mapped above 4GByte (reg04 and reg05).
> > > 
> > > -wolfgang

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