Memory in top command smaller than BIOS
by Cemmac from LinuxQuestions.org on (#6D4EJ)
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
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