On Fri, Dec 09, 2016 at 06:50:45AM +0100, John Darrington wrote:
> Building qemu invariably results in the following:
> 
> PASS: tests/test-filter-redirector
> TEST: tests/postcopy-test... (pid=25237)
>   /i386/postcopy:                                                      building of `/gnu/store/rjbql3m2w6mcy0l21m5r6jkaz8mw8z4r-qemu-2.7.0.drv' timed out after 3600 seconds of silence
> @ build-failed /gnu/store/rjbql3m2w6mcy0l21m5r6jkaz8mw8z4r-qemu-2.7.0.drv - timeout
> guix build: error: build failed: build of `/gnu/store/rjbql3m2w6mcy0l21m5r6jkaz8mw8z4r-qemu-2.7.0.drv' failed

Is this on 32-bit or 64-bit x86?

1 hour does seem excessively long. Did you try tracing the process to
see if it's actually working?

If it is working, did you try increasing the value of
'--max-silent-time' beyond 3600 seconds? Is the machine in question very
slow?