make the gc return an int
gc returns an int
no need for vmqueue in the handle
take a shot at attempting to actually unlink a deceased thread
implementation of Huelsbergen-Winterbottom VCGC
use xvindex to initialise (so we don't have to bother with the write barrier)
do not use scar/scdr when initialising a cons to avoid the write barrier
allocator definitions for VCGC
avoid using the write barrier when initialising objects
stub out check_gc until we have a version for VCGC
initialise variables properly
perform three iterations of the gc after clearing to cause the gc to free all the memory it used
when initialising do not use the write-barrier enabled functions to do so
get markprop to mark symbols (i.e. their buckets) properly
reduce default quantum to 4096
do not mark twaitfd (it isn't a value!)