Why is LuaJIT's memory limited to 1-2 GB on 64-bit platforms?

Question

On 64-bit platforms, LuaJIT allows only up to 1-2GB of data (not counting objects allocated with malloc). Where does this limitation come from, and why is this

Answer 1

Due to recent patch luajit 2GB memory limit can be solved.

To test, clone this repo and build with LUAJIT_ENABLE_GC64 symbol defined:

msvcbuild.bat gc64

or XCFLAGS+= -DLUAJIT_ENABLE_GC64 in Makefile

I used this code to test memory allocation:

local ffi = require("ffi")

local CHUNK_SIZE     = 1 * 1024 * 1024 * 1024
local fraction_of_gb = CHUNK_SIZE / (1024*1024*1024)
local allocations    = {}

for index=1, 64 do
    local huge_memory_chunk = ffi.new("char[?]", CHUNK_SIZE)
    table.insert(allocations, huge_memory_chunk)
    print( string.format("allocated %q GB", index*fraction_of_gb) )
    local pause = io.read(1)
end

print("Test complete")
local pause = io.read(1)

Allocated 48GB before not enough memory error on my machine.