Sub 512MB RAM Devices

[skyhawk3355]

Hi all,
Doing a fun project where I’m trying to take FOG images of era appropriate windows 98 machines. I’ve found a small problem with the amount of RAM FOS requires and the RAM that is physically available to these computers. I don’t have hard numbers but with 512mb I can boot and image without issues. With my 384Mb computer it’ll boot to the menu but will freeze on inventory or imaging.

I’ve looked into recompiling the kernel
https://wiki.fogproject.org/wiki/index.php?title=Building_a_Custom_Kernel
however this line has me worried
Important: All settings required by fog are already in the kernel,…

Without adding RAM (I’d like to image even older machines), what would the best way to fit FOS onto these RAM limited computers?

[Tom Elliott]

@skyhawk3355 FOG has been able to be loaded into 256mb of ram for quite some time.

It was originally configured for 128MB of ram, but that was in 2007.

If we know how much RAM is on the actual machine?

I believe all our kernels and init need at least 200mb of ram to operate.

[george1421]

@skyhawk3355 said in Sub 512MB RAM Devices:

ith my 384Mb computer it’ll boot to the menu but will freeze on inventory or imaging.

To just add a little clarity here. The iPXE menu is under the control of iPXE. Once you pick a menu item FOS (bzImage and init.xz) is loaded into memory and executed.

Both bzImage and init.xz are compressed images, so the size on disk is not indicative of the space consumed in RAM. Both are decompressed as they are loaded into memory. I’d have to look to verify, but I think bzImage is in the 8MB range and init.xz is in the 200mb range.

If you just consider the baselines of a standard gzip compression ratio of 1.6:1, the kernel will expand to 13MB, and the 200MB init.xz would expand to 332MB. That puts us at 345MB for just the image to be held in memory. That leaves almost no ram to execute FOS. Just to caveat this, I have not looked at what the current size of bzImage and init.xz are.

Now if you have no choice, surely look into the 32 bit version of FOS linux since it should consume less space. But with 384MB of ram, that is going to be very tight.

Second option is to remove the hard drive from the computer and image it on a system that has a bit more resources, then place the drive back into the limited computer for first boot.

[skyhawk3355]

Thank you guys for your insight. Using the 32 bit version did get me further during inventory but resulted in a kernel panic error.
manually adding the host to fog and running a capture task still ends frozen on a flashing cursor after “random: crng init done”.
I was able to scrounge another 256mb module, bringing the total RAM to 512 and was able to capture a image without issue.

[george1421]

@skyhawk3355 I remember awhile ago I needed to create a one-off kernel for a system that had a 486 cpu. I checked but I don’t have that kernel any more.

I just recompiled the linux 6.6.85 for a 586 based CPU. I can recompile for a 486, but I don’t know if that is going to get us anything better.

Here is 6.6.85 586 version
https://drive.google.com/file/d/1GAzFjbtpDVXXCRpe6bIZ5mwySSXeDHko/view?usp=drive_link

Here is 6.6.85 586 where I stripped out some drivers like scsi, nvme, uncommon network drivers, virtualization drivers, etc. I was able to strip out over 1MB of kernel size from the previous one above. Did I through out too much?? YMMV.
https://drive.google.com/file/d/13dE7BLgofsFiNJj_Q8nLDknplRbWRqkJ/view?usp=drive_link