Re: Problems with AMD64 and 8 GB RAM?

From: Peter Wemm (peter_at_wemm.org)
Date: 03/31/05

  • Next message: Ask Bjørn Hansen: "Re: Problems with AMD64 and 8 GB RAM?" 
    To: freebsd-amd64@freebsd.org
Date: Wed, 30 Mar 2005 15:22:27 -0800

    On Wednesday 30 March 2005 03:15 pm, Greg 'groggy' Lehey wrote:
    > On Wednesday, 30 March 2005 at 16:01:14 -0700, Scott Long wrote:
    > > Greg 'groggy' Lehey wrote:
    > >> On Wednesday, 30 March 2005 at 14:35:46 -0800, Steve Kargl wrote:
    > >>> On Thu, Mar 31, 2005 at 07:54:39AM +0930, Greg 'groggy' Lehey
    wrote:
    > >>>> None of these problems occur when I use 4 GB memory. About the
    > >>>> only strangeness, which seems to come from the BIOS, is that it
    > >>>> recognizes only 3.5 GB. If I put all DIMMS in, it recognizes
    > >>>> the full 8 GB memory.
    > >>>
    > >>> I had 4 bad out of 12 tested where the DIMMs were Crucial PC2700
    > >>> 2GB Reg. ECC DIMMs.
    > >>
    > >> OK, this makes sense. It might also explain why the 4 GB
    > >> configuration only recognizes 3.5 GB.
    > >
    > > No, and I'm going to make this an FAQ and post it in a very obvious
    > > place, since 4+ GB is so easy to get and people don't seem to
    > > understand the PC architecture very well.
    >
    > That's not easy to understand when it's barely documented. Thanks
    > for the info: it helps a lot.
    >
    > This may still be a hint, though: that memory hole doesn't show up
    > during a boot with 8 GB RAM. How come? Is the system trying to map
    > RAM over the PCI hole?

    Nope, its still there. When you boot -v, you'll see the hole in the
    "Physical memory chunk(s)" list.

    However, I suspect that some of the bioses will set the 4GB hole
    partition in the physical ram lower so that there will be 4.5GB of ram
    above the 4GB mark. I haven't looked too closely to see for sure.

    > It looks as if I should get a verbose boot listing with 8 GB. It'll
    > be a couple of hours before I find time to reboot this machine. In
    > the meantime, there's a verbose boot with 4 GB at
    > http://www.lemis.com/grog/Images/20050331/obelix-dmesg. I'm told it
    > shows a number of strange things, including incorrect reporting of
    > on-chip cache sizes.

    Nope, it is correct. You have 1MB of L2 cache.
    L1 data cache: 64 kbytes, 64 bytes/line, 1 lines/tag, 2-way associative
    L1 instruction cache: 64 kbytes, 64 bytes/line, 1 lines/tag, 2-way
    associative
    L2 unified cache: 1024 kbytes, 64 bytes/line, 1 lines/tag, 16-way
    associative

    > Greg
    > --
    > See complete headers for address and phone numbers. 

    -- 
Peter Wemm - peter@wemm.org; peter@FreeBSD.org; peter@yahoo-inc.com
"All of this is for nothing if we don't go to the stars" - JMS/B5
_______________________________________________
freebsd-stable@freebsd.org mailing list
http://lists.freebsd.org/mailman/listinfo/freebsd-stable
To unsubscribe, send any mail to "freebsd-stable-unsubscribe@freebsd.org"
  • Next message: Ask Bjørn Hansen: "Re: Problems with AMD64 and 8 GB RAM?"

    Relevant Pages

    • Re: Fast Start-up
      ... If you can keep the RAM live, then why can't you just suspend? ... like a car battery, and nobody wants your device to accidentally drain that ... Faster processors generally boot faster. ...
      (microsoft.public.windowsce.embedded)
    • Re: Making a L440GX+ work (was "Trying to revive a server... AIC-7896 freezes pre-POST compl
      ... You should be able to update the BIOS from a floppy or cd-rom boot disk. ... The general rule with ram is you can run faster ram than you need, just usually wastes money that faster RAM costs. ... That jumper should reset the BIOS to factory defaults to allow it to get through the post and into setup. ... I know this isn't a FreeBSD question really, but I just started up a motherboard with onboard SCSI, and for some odd reason it freezes pre-POST before it attempts to boot and there isn't any way where I can get into the BIOS to change the settings it seems. ...
      (freebsd-questions)
    • Re: WinCE boot from RAM with Lauterbach trace32
      ... The problem to boot eboot and WinCE6.0 from RAM using Lauterbach Trace32 has ...
      (microsoft.public.windowsce.embedded)
    • Re: WinCE boot from RAM with Lauterbach trace32
      ... Reset the CPU and break at 0x0 ... The problem to boot eboot and WinCE6.0 from RAM using Lauterbach Trace32 ...
      (microsoft.public.windowsce.embedded)
    • Re: Opteron box and 4Gb memory
      ... The memory was not paired, so the motherboard was not interleaving the access. ... My processors are higher than Rev E0, because the BIOS does not let me choose ... If I activate the 'hardware hole', ... The ram is DDR 400. ...
      (Linux-Kernel)