linux: when are vmalloc & uppermem required?

The NVIDIA CUDA Linux Release Notes (currently here:…_1.1_linux.txt) quote:

"On some Linux releases, due to a GRUB bug in the handling of upper
memory and a default vmalloc too small on 32-bit systems, it may be
necessary to pass this information to the bootloader:

vmalloc=256MB, uppermem=524288"

Can someone please advise when these settings are required? Ie. what would the defect be, what wouldn’t be working, what is fixed by this setting?

[I am having some driver / machine crashes and I wish to know if this setting might be worth trying.]

thanks - David.

Those settings are only required if the OS fails to boot. It is really unrelated to CUDA.