# [SOLVED] OS sees only half of the RAM

## AgBr

I have a brand new Fujitsu TX150 S7 with one Xeon X3430 and 4GB of RAM.

I have confirmed that $GB is physically installed (one Bank) and that the BIOS sees the RAM. Problem is that the OS sees only half of it.

```

Linux 3.2.12-gentoo #1 SMP PREEMPT Fri Apr 20 07:57:20 CEST 2012 i686 Intel(R) Xeon(R) CPU X3430 @ 2.40GHz GenuineIntel GNU/Linux

cat /proc/meminfo 

MemTotal:        2062392 kB

MemFree:         1584644 kB

Buffers:           30264 kB

Cached:           261884 kB

SwapCached:            0 kB

Active:           244928 kB

Inactive:         196676 kB

Active(anon):     149580 kB

Inactive(anon):      284 kB

Active(file):      95348 kB

Inactive(file):   196392 kB

Unevictable:           0 kB

Mlocked:               0 kB

HighTotal:       1179336 kB

HighFree:         762448 kB

LowTotal:         883056 kB

LowFree:          822196 kB

SwapTotal:       4128668 kB

SwapFree:        4128668 kB

Dirty:                96 kB

Writeback:           368 kB

AnonPages:        149460 kB

Mapped:            11028 kB

Shmem:               408 kB

Slab:              24240 kB

SReclaimable:      10416 kB

SUnreclaim:        13824 kB

KernelStack:        1216 kB

PageTables:          808 kB

NFS_Unstable:          0 kB

Bounce:                0 kB

WritebackTmp:          0 kB

CommitLimit:     5159864 kB

Committed_AS:     419696 kB

VmallocTotal:     122880 kB

VmallocUsed:        7116 kB

VmallocChunk:     105444 kB

HardwareCorrupted:     0 kB

HugePages_Total:       0

HugePages_Free:        0

HugePages_Rsvd:        0

HugePages_Surp:        0

Hugepagesize:       4096 kB

DirectMap4k:       12280 kB

DirectMap4M:      897024 kB

dragon ~ # 

 
```

May be someone can give me some hint, what to look for in the kernel config. I am using a 32 Bit kernel. This has never been a problem with up to 6GB in the past wtih older kernels.Last edited by AgBr on Mon Jun 11, 2012 7:03 pm; edited 1 time in total

----------

## audiodef

1. Have you copied your old kernel config, or started from defconfig with your current kernel?

2. Try setting up a kernel seed as per the seeds mirror link in my sig, and let me know if that helps.

----------

## Ant P.

Since you're using 32-bit, you need 4GB PAE enabled at a bare minimum.

----------

## AgBr

I  just had a look.

I have PAE Support enabled

High Memory Support is for 4GB. I have set it to 64GB. The new kernel is building right right now, as I am to increase the memory to 8GB in the next days. But this should not make a difference now.

----------

## AgBr

 *audiodef wrote:*   

> 1. Have you copied your old kernel config, or started from defconfig with your current kernel?
> 
> 2. Try setting up a kernel seed as per the seeds mirror link in my sig, and let me know if that helps.

 

Thank you for that link. Extremely interesting. 

My config is derived from Knoppix. Why that?

I am installing a homebrew binary-gentoo system on a lot of different hardware for different purposes. We are a school and I support about 100 boxes in my domain. Mostly clients but some servers too. The machine in question here is a virtualization host. My first one. I had a lot of work with this one but when I am done I can install them by booting into a pxe-System or from USB-Stick and starting a script within minutes without manual intervention. The downfall of this is that I need a one size fits all kernel config, the best I have found is that of Knoppix. A new kernel gets built on the build-server by running make oldconfig automatically whenever a new kernel is out. The downfall is, that I have to live with the default options. Only when I find new hardware not previously supported, I have to make a new kernel by hand test it and put the config onto the build-server. This is extremely rare.

Just in case anyone asks. I haven't created the system, I am just maintaining it as good as I can.

----------

## audiodef

That sounds pretty nifty. You should document it and share it somewhere on these forums.   :Smile: 

----------

## AgBr

 *audiodef wrote:*   

> That sounds pretty nifty. You should document it and share it somewhere on these forums.  

 

It is pretty nifty, but as I said: I am not the author, I am just maintaining it. It's not up to me to publish it. As far as I know the author is working on an improved version. I hope he'll put it in an ebuild.

----------

## AgBr

 *AgBr wrote:*   

> I  just had a look.
> 
> I have PAE Support enabled
> 
> High Memory Support is for 4GB. I have set it to 64GB. The new kernel is building right right now, as I am to increase the memory to 8GB in the next days. But this should not make a difference now.

 

Increasing High memory support from 4G to 64 did the trick.

Thank you all or your advice

----------

## Mad Merlin

For VM hosts, a 64-bit kernel would be strongly recommended, for both technical (it'll be faster and much better tested) and practical reasons (nobody runs a VM host with <4G of ram in this day and age). Incidentally, Red Hat doesn't even package KVM for 32-bit RHEL, only 64-bit RHEL.

You can go ahead and use a 32-bit host if you want, but keep the above in mind if you run into weird problems.

----------

## AgBr

 *Mad Merlin wrote:*   

> For VM hosts, a 64-bit kernel would be strongly recommended, for both technical (it'll be faster and much better tested) and practical reasons (nobody runs a VM host with <4G of ram in this day and age). Incidentally, Red Hat doesn't even package KVM for 32-bit RHEL, only 64-bit RHEL.
> 
> You can go ahead and use a 32-bit host if you want, but keep the above in mind if you run into weird problems.

 

Thank you for this heads up. I will take this into consideration. It is difficult for me to install different kernels in my current framework. May be I will have to abandon the automatic update process for the kernel in some way after installation and then build the kernel locally. 

EDIT: Just thought this over. It would require me to maintain a second build-system in parallel to the current one as it's not just the kernel but the whole system to be 64Bit. As my goal is not hardware consolidation but easier cloning and maintaining the guest (two in max) I will have to think about whether it is worth the effort.

----------

