Messages in this thread | | | Date | Tue, 8 Aug 2006 11:13:00 +0200 (MEST) | From | Mikael Pettersson <> | Subject | Re: Only 3.2G ram out of 4G seen in an i386 box |
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On Tue, 8 Aug 2006 09:24:29 +0100, Thomas Stewart wrote: > I have a Dell Optiplex GX280, a Pentium 4 with an Intel chipset. It has > 4G of ram. The problem is I can only see 3.2G, even tho the bios reports > 4G. > > While using debian 2.6.16-2-686: > thomas@coke:~$ uname -a > Linux coke 2.6.16-2-686 #1 Sat Jul 15 21:59:21 UTC 2006 i686 GNU/Linux > thomas@coke:~$ grep MemTotal /proc/meminfo > MemTotal: 3375484 kB > > This is expected as the standard debian kernels don't set > CONFIG_HIGHMEM64G. My understanding is that this needs to be set for the > full 4G to work on i386. > > So I downloaded 2.6.18-rc3-git3 and 2.6.18-rc2-mm1 to give them a try. I > used the debian config as a starting point for oldconfig. Then from > menuconfig, "Processor type and featues" -> "High Memory Support" and > selected 64G. I then compiled both, rebooted and got these results: > > 2.6.18-rc2-mm1 reported MemTotal: 3376192 kB > 2.6.18-rc3-git3 reported MemTotal: 3376236 kB
Most likely the BIOS is reserving large parts of the [0,4GB[ range for PCI devices and some for itself. Please post the E820 memory map the kernel prints near the start of the boot sequence on your machine.
> Is there anything I can do to make use of the 800M or so of ram that's > unused? Changing to amd64 or anything else that's sane or better does > not count ;-)
You need a chipset+BIOS that can relocate RAM to above the 4GB boundary. I don't know how common those are in the 32-bit x86 world. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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