The canonical way to get the GPU memory is with
vcgencmd get_mem gpu
If your distro doesn't provide that, you can build it with the source tree that also includes
raspicam and the userspace GPU libs:
However, you probably don't need to go to that much trouble if you just want to confirm the split is set, because for every MB of GPU allocated you have one less MB of RAM, and there are all kinds of ways to check that (try
free -h and check the top row
grep memory /var/log/Xorg.0.log returned only 2,839kB:
[ 132.909] (II) FBDEV(0): hardware: BCM2708 FB (video memory: 2839kB)
I don't think that number has much to do with the GPU/RAM split, and I don't think "video memory" refers to actual physical video memory. It might WRT other Xorg drivers for different hardware, but the framebuffer driver is for a software construct provided by the kernel (FBDEV = framebuffer device).1
I don't have any pis running X right now to check, but looking through logs from old backups of systems where I did at least occasionally, that would also have been running cameras (requiring >= 128 MB GPU), that number varies between 1500 kB and 7100 kB.
Finally, the GPU requires a minimum of 16 MB. You can't set it less than that, so it must be at least 16384 kB.
- Looking at the Xorg log for this laptop, which has a dual video card one part of which is a beefy nvidia thing, there's no numbers at all reported for video memory, although I do seem to believe I've seen it before.