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Old 07-20-2023, 04:36 AM   #1
Cemmac
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Memory in top command smaller than BIOS


Hello,

We have some industrial PC with some old linux (redhat) on SuperMicro server. The memory slots in BIOS detect 4GB, in OS command of 32bit Linux in top, free, cat /proc/meminfo everywhere shows only 2,5GB.

There is some extension PCI device card (Gidel Procstar FPGA card) which connect CNC machine movement, camera, etc.

When card is in PCI slot linux shows 2,5GB, if put it out it shows as normal 4GB.

I was first think it is something wrong with driver for device, maybe some BIOS setting, then also someone mention Memory reservation allocation in kernel. I'm not really so deep in linux, but i imagine it could make that PCi device takes those addresses of memory and cover physical memory in OS.

The thing is that in original OS Linux system works OK, but HDD fails in it. After that we get new spare HDD which by provider says it is the same only drivers need to be installed.



Thank you for help

Last edited by Cemmac; 07-20-2023 at 04:51 AM.
 
Old 07-20-2023, 04:45 AM   #2
Cemmac
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To add:

It si different memory mapping, when we booting Linux.

https://ibb.co/fVRHYpq - PCI device inside
https://ibb.co/JdNxQcW - PCI not inside
 
Old 07-20-2023, 06:15 AM   #3
mrmazda
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Old 32bit PCs commonly can access only ~3GB of RAM. If the graphics shares RAM, this can be reduced farther. What does
Code:
sudo inxi -mGaz
report using the inxi from here.
 
Old 07-20-2023, 06:29 AM   #4
Cemmac
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inxi command not found..
 
Old 07-20-2023, 06:42 AM   #5
mrmazda
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Quote:
Originally Posted by Cemmac View Post
inxi command not found..
Using the inxi from the provided URL along with the instructions there provided there's no reason for a not found error to occur. Inxi is not a standard inclusion in most distros, particularly in old ones. Even new ones commonly provide old versions of it.
 
Old 07-20-2023, 06:34 PM   #6
Arnulf
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Are your Supermicro servers 32-Bit (ia32) or 64-Bit (x86_64) machines?
 
Old 07-21-2023, 01:24 AM   #7
lvm_
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Wikipedia is your friend https://en.wikipedia.org/wiki/PCI_hole
 
Old 07-25-2023, 07:07 PM   #8
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Memtest?
 
  


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