Allow the user to pick the address that the RTS reserves for the heap

We stumbled upon a case where an external library (OpenCL) does not work if a specific address (0x200000000) is taken.

It so happens that osReserveHeapMemory starts trying to mmap at 0x200000000:

        void *hint = (void*)((W_)8 * (1 << 30) + attempt * BLOCK_SIZE);
        at = osTryReserveHeapMemory(*len, hint);

This makes it impossible to use Haskell programs compiled with GHC 8 with C functions that use OpenCL.

See this example https://github.com/chpatrick/oclwtf for a repro.

My proposal is to allow the user to work around this kind of behavior outside our control by letting the user override the starting address through an RTS command line flag.

Trac metadata

Trac field	Value
Version	8.0.1
Type	FeatureRequest
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Runtime System
Test case
Differential revisions
BlockedBy
Related
Blocking
CC	simonmar
Operating system
Architecture