OpenSBI 1.3 an newer require the heap_size to be specified in the
sbi_platform structure, othewise the default 0 value causes a hangg at
the start. I found the problem after bisecting OpenSBI:
# Bisect opensbi
version = src.shortRev;
src = builtins.fetchGit {
url = "file:///home/Computational/rarias/riscv/opensbi";
#rev = "908be1b85c8ff0695ea226fbbf0ff24a779cdece"; #good
#rev = "6bc02dede86c47f87e65293b7099e9caf3b22c29"; #good
#rev = "bbff53fe3b6cdd3c9bc084d489640d7ee2a3f831"; #bad
#rev = "8b99a7f7d8294be29e18a667d51e13755ed2c0e0"; #good
#rev = "bdde2ecd27af1ac158669809f6658376fb5137ab"; #good
#rev = "5cf9a540164a018a31a679578a27eb964af0340d"; #good
#rev = "2a04f7037317c6c5b591b160a074c700de9b3378"; #bad
rev = "40d36a6673131e36075b1df78af4d7ab92e8cc01"; #bad
};