At least up until DR2.1, MkLinux doesn't save and restore a register
specific to the 601 (the MQ register) which gcc uses when you give it
the -mcpu=601 option. This causes it to be corrupted every time there
is an interrupt, which not surprisingly causes problems with any
program using it.

The only obvious solution is not to use the -mcpu=601 option.
-mcpu=powerpc is a similar but slower substitute.

- Geoff Keating <Geoff.Keating@anu.edu.au>

This is fixed in at least DR2.1u4 and later.