Gentoo Archives: gentoo-user

From: Andrew Frink <andrew.frink@×××××.com>
To: gentoo-user@l.g.o
Subject: Re: [gentoo-user] weird 4GB RAM and kernel issue
Date: Sun, 02 Apr 2006 07:20:17
Message-Id: 8146fc8a0604012315q5b85d31r97a9bb68d3164838@mail.gmail.com
In Reply to: [gentoo-user] weird 4GB RAM and kernel issue by kashani
1 On 4/1/06, kashani <kashani-list@××××××××.net> wrote:
2 >
3 > I've made my problem go away, but I'm a bit curious about why it
4 > was
5 > happening.
6 >
7 > I've got nine or so Dell 1850's with 2 x 2GB chips. When I compile
8 > gentoo-source 2.6.15-r1 (and 2.6.14-r5) with support for 4GB I see only
9 > 3GB. 1GB lowmem and 2GB highmem.
10 >
11 > ws04 ~ # cat /proc/meminfo
12 > MemTotal: 3107408 kB
13 > MemFree: 1731660 kB
14 > Buffers: 219720 kB
15 > Cached: 937980 kB
16 > SwapCached: 0 kB
17 > Active: 455100 kB
18 > Inactive: 717924 kB
19 > HighTotal: 2227968 kB
20 > HighFree: 1271588 kB
21 >
22 > When I recompile on the same hardware with support for 64GB RAM I see
23 > the full 4GB in the usual 1GB/3GB split.
24 >
25 > nms02 ~ # cat /proc/meminfo
26 > MemTotal: 4147776 kB
27 > MemFree: 3762712 kB
28 > Buffers: 151404 kB
29 > Cached: 45116 kB
30 > SwapCached: 0 kB
31 > Active: 56724 kB
32 > Inactive: 145000 kB
33 > HighTotal: 3276544 kB
34 > HighFree: 3222936 kB
35 >
36 > However on my HP DL360 with 4 x 1GB RAM I see the 4GB, though it's a bit
37 > smaller, with 4GB enabled in the kernel. Same kernel version as the
38 > Dell's.
39 >
40 > ramin@azul ~ $ cat /proc/meminfo
41 > MemTotal: 3977744 kB
42 > MemFree: 116792 kB
43 > Buffers: 296108 kB
44 > Cached: 3157952 kB
45 > SwapCached: 0 kB
46 > Active: 2725152 kB
47 > Inactive: 782956 kB
48 > HighTotal: 3096552 kB
49 > HighFree: 8680 kB
50 >
51 > I've been Googling around for an explantion, but am not really sure what
52 > I'm looking for. I'd assume that I might lose a few hundred MB if the 2
53 > x 2GB chips are slightly bigger than the 4GB limit rather than the full
54 > 1GB that seems to disappear. I'm guessing some wacky motherboard
55 > interleaving thing where highmem ends up being one chip and the lowmem
56 > the 896MB on the other chip.
57 >
58 > Anyone have a decent theory on this with a nice link?
59 >
60 > kashani
61 > --
62 > gentoo-user@g.o mailing list
63 >
64 >
65
66 this is the same thing that happens at the 800-1G spot... a machine with 1G
67 need to enable 4G supprt to see it all