Hello Svante, I have a few recommendations, places where I'd check: 1. Consult the arguments passed to read() usign GDB (your libc has debugging symbols) and see if they are obviously wrong. It seems more plausible that they are something that would be right for Linux, but not so right for Hurd. 2. Take the source code for ghc-pkg, and start adding debug prints, checking to see if the print is triggered or not (it will be useful if you can figure out what command you can run to just recompile ghc-pkg). See if you can reduce the program to a minimal one that still hangs. 3. Compile GHC with the flag -ddump-stg, and pipe all of this output to a file. With any luck, the block s9qJ will have been present during this stage, at which point you can use it to trace back to a file. Note that due to lazy evaluation, s9qJ is probably /not/ actually the culprit, which is why I recommend doing (2) first; it's a lot easier to wade around smaller bits of code. Another recommendation is to bootstrap 6.8.3. (the last 6.8 release) first, before attempting 6.10.1. Edward