document disabled "GPU" features when setting gpu_mem <64 MiB

[txt-file]

In

documentation/documentation/asciidoc/computers/legacy_config_txt/memory.adoc

Line 35 in 8146e76

It is possible to set `gpu_mem` to larger values, however this should be avoided since it can cause problems, such as preventing Linux from booting. The minimum value is `16`, however this disables certain GPU features.

you write "The minimum value is 16, however this disables certain GPU features.". I want to know which features are disabled by which limit. Something like

• is video encoding still possible with 16/20/32/40/50/64 MiB gpu_mem?
• is video decoding still possible with 16/20/32/40/50/64 MiB gpu_mem?
• is "L2 cache" still available with 16/20/32/40/50/64 MiB gpu_mem?
• what other features are enabled/disabled?

[lurch]

See https://www.raspberrypi.com/documentation/computers/configuration.html#start-elf and https://www.raspberrypi.com/documentation/computers/config_txt.html#start_file-fixup_file

[txt-file]

@lurch So gpu_mem=17 does not limit anything?