Installation guide

OS-9 V2.4 on EUROCOM-17 2 Installing OS-9 V2.4.5
Software Manual 9
2.4.4 Notes and
Restrictions
The DDIO bit in module init is set by default. This tells the kernel not to
disable the data cache when in I/O.
Disabling data cache is required for systems with drivers which use DMA
and don't perform any explicit data cache flushing. If your system does not
use DMA drivers, or the drivers care for the cache, the DDIO bit should be
set.
The DDIO bit has to be modify by the label NoDataDis in systype.d. If
you want to unset the DDIO bit, set to comment the label NoDataDis in
DEFS/systype.d and remake the init module.
The syscache040/ssm040 modules are only for 68040 and 68LC040
systems. For 68EC040 configuration, see Section2.4.2 ‘OS-9
Configuration without SSM’.
If you want to set breakpoints in the system level debugger, the caches
have to operate in write through mode!