Limits on various things

Sarld can only be 128k long (when loaded).
Drivers relocatable files can't be bigger than 320K.
Kernel symbols can't be bigger than 512k.
Sarld can't use more than 1024k of malloc memory.
Kernel symbols can't be more than 512k bytes long.
Kernel + drivers can't be more than 5.5Mb.

The memory map and sizes of various things are in libsa/memory.h.