What to do to notify system of hardware changes, systemd-boot params

Ask Fedora
1

(Expertise implies specialization. Specialization is not all-knowing. An expert might not even know everything with in his/her own narrow specialization. If I am a tor developer, do I really know everything about Fascist Firewall? If there is anything to know. We don’t know what we don’t know and mind-reading is our own self-delusion projecting our own insecurities. Maybe there is something I don’t know.)

So, what do you do on Fedora (39) to notify the kernel and proc of meminfo changes? Say I add RAM to my hardware but the kernel still thinks the original state is the current composition of the hardware? Does the system use the full hardware capability anyway without having been notified of the increase?

Changing the parameter in GRUB (mem=xxM) and then regenerating with grub2-mkconfig seems straight forward enough but doesn’t F39 use EFI systemd-boot? Is there a simple way to make a modification with bootctl?

If I have 24 GB can I call that 24000M or 23999M? cat /proc/meminfo usually displays a number less that perfectly round, as is true of disk space.

What if I add a physical CPU just out of curiosity? Are kernel boot parameters the place to profile system hardware post-installation?

Thanks!

2

Kernel parameters to not specify RAM. All available RAM is used by the system and no grub parameters or kernel options are required (by any OS). You should know this if you are as specialized and expert as your username indicates.

3

The amount of supported RAM can be limited by the manufacturer.
You should check the documentation on your system board.
BIOS updates can sometimes fix incorrect RAM limitations.

4

@computersavvy Please!

5

Correct, but that does not normally prevent the kernels from using all RAM that is made available by the bios. It does in many cases restrict the size of the RAM DIMMs that are supported on the board and is a bios or hardware limitation and not a kernel limitation.

6

Never mind. There is something physically wrong with the Apple memory.

meminfo finds the available RAM every time the system starts.

2 sticks of 8GB somehow still equaled 4GB meaning 2 Kingston chips are disabled on each stick but the RAM is still functional. Strange. Need a chip lab to look at the hardware, I suppose. Mystery joke. Haha! :star_struck: