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Re: why linux can't see my memory

Long Wind wrote:

On 1/5/14, Miles Fidelman <mfidelman@meetinghouse.net> wrote:

If you have a memory hole, chances are there wouldn't be a BIOS option
to help.  It has to do with the way that memory-mapped i/o is handled
with some families of chips and their associated motherboards.

For example, I have two older servers - fully loaded with 4Gig of RAM
(as I said, older servers) - but no way, no how does the system see more
than 3G.  The other 1G is taken up by memory mapped i/o space.  It's a
hardware design issue, not a BIOS issue.  (For reference: P4 640
processor, Supermicro P8SCT motherboard).

In addition to the reference I sent earlier, this sort of describes the
issue: http://en.wikipedia.org/wiki/3_GB_barrier
and this: http://www.dansdata.com/askdan00015.htm
If you do some googling, you'll also find an Intel design note that's
the definitive description of the issue (I can't seem to find it right now)

Some BIOSs support "memory hole remapping," but others don't - and that
assumes the underlying chipset and motherboard will support it.  A lot
don't.

Of course this might not be the problem you're seeing.  What CPU,
chipset, motherboard, and BIOS are you running?


Thanks!

CPU is P4/2.9G, motherboard is  848P-M7
it's quite like 848P-M Deluxe:

http://www.ecs.com.cn/ECSWebSite/Product/Product_Detail.aspx?CategoryID=1&DetailID=402&DetailName=Feature&MenuID=24&LanID=0

actually I might try to update BIOS from site above
model numbers are the same, it's not recommended to update
but it seems I have no other choice
if motherboard become unusable, my trouble also ends

I can't fully understand technical details you describe
the point I want to repeat is the machine can run Windows XP
and in memtest it's OK after configuration

Linux fail here, (or does it?)
That's a pretty ancient chip set, and it looks like your motherboard won't hold more than 2G. I expect the memory hole is NOT your problem, as it would restrict you from seeing the top 1G of 4G, I don't think it would keep you from using all 1G, but then again, I'm just a little foggy on whether there are situations where the bottom of your address space would be shadowed.
I'd follow Scott Ferguson's advice, try to get Knoppix to boot and then see what dmidecode tells you. Or maybe burn a copy of SystemRescueCD (http://www.sysresccd.org/SystemRescueCd_Homepage) and see if you can boot from it, then start poking around with some of the tools on it (e.g., hwreport). 

Miles Fidelman



--
In theory, there is no difference between theory and practice.
In practice, there is.   .... Yogi Berra
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